Low-external Input Rice Production - Chapter 4 - Water Management / Cropping Patterns

Water management for rice in drought-prone locations

A number of strategies exist for farmers to minimize risks and reduce losses in drought-prone and rain fed rice-producing areas. These strategies focus mainly on the following: varietal selection, timing of planting to minimize drought damage, maintenance of water level, cultural practices aimed at conserving water or improving drought resistance and altering the physical farm environment.

1. Varietal selection

· Select drought-tolerant varieties if drought is likely to occur. In general, IRRI found droughttolerant rice varieties to have long, dense and thick roots. Traditional varieties like BE-3, Peta and Intan tolerate some drought but yields are lower than modern varieties. The IRRI varieties IR6, IR46 and IR64 also withstand mild drought although IR36 and IR64 are prone to tungro disease.

· Plant very short-duration varieties to avoid the drought period entirely.

2. Timing of-planting

· Plant the rice such that the vulnerable reproductive stage does not fall during the drought season. This presupposes a regularly occurring drought in a region which the farmers anticipate and plan around.

· Synchronize planting with neighboring farmers to minimize irrigation water wastage.

Timing of-planting 

3. Maintenance of water level

· It is important to provide the crop enough water to induce maximum tillering (formation of stalks) for a good cover (canopy) so that water losses by evaporation would be minimized.

· Water is essential during flowering on from 55-70 days after transplanting of the shortduration varieties. If simultaneous planting is done, 800-1,000 mm of water would be minimum requirement.

· Fields need only be kept moist (not flooded) all the time with a 1-2 mm layer as minimum. Using this strategy gives a 30-50% cut requirements without yield losses.

4. Other cultural practices

· Maintain rice paddy dikes to minimize seepage and clean irrigation ditches regularly.

· Establish good weed control. Most weeds are much more efficient than rice in exploiting soil moisture.

· Supply nitrogen (N) and other fertilizers early. If using less than 30 kg N/ha, apply all of it basally. If applying more than 30 kg N/ha, use the best split (2/3 basal and 1/3 topdress 5-7. days after panicle initiation [DAP]). This improves the plant's drought resistance by encouraging faster root growth and, thus, more soil area can be exploited for soil moisture.

· Increase soil organic maker (OM) content. OM improves the soil's water absorption and retention capacity.

· Minimum tillage (one plowing and one harrowing) reduces the water requirement for land preparation and speeds crop establishment, lowering the risks of an end-of-season drought. Minimum tillage is possible in fields where perennial weeds are few.

· Direct seedling of pregerminated seed can be used where there is not enough water to thoroughly prepare the land for transplanting. Direct seeding also results in a stronger root system. This gives the crop batter capacity to survive during short drought.

· Farmers should use the early rains of May for land preparation since this water largely goes to waste.

5. Altering the physical farm environment

· If feasible, impound water in one-fifth of the land area. A 200 sq.m structure will be enough to supply the water for a half hectare of rice crop and could also be used for fish production.

· Reduce the area planted to rice to increase the amount of irrigation or residual rainfall water available. The Sorjan system developed by farmers in Indonesia is one such method of water management. Tests done in Indonesia show that this system nearly doubled the amount of available water for rice production. Devote low-lying areas of the farm to rice and plant the upper areas with dryland crops. The rice crop can take advantage of the higher water table in the lower areas and can utilize runoff from the upper areas. (See the technology sheet on Sorjan: Towards Rice-based Integrated Cropping System.)

· Plant windbreaks to reduce evapotranspiration of the rice crop.

· At the national level, deforestation is the main cause of irrigated water shortages for rice production. For long-term sustainability, the nation's mountainous area must be reforested.

Legume crop rotation with rice

INTRODUCTION:

In rainfed lowland areas which are traditionally planted to only one crop of rice per year, land use can be optimized by using the pre- and/or post-rice wet period to grow-legume crops. Legumes are suitable rotational crops with rice because they:

· can mature in 55-90 days.

· can be grown as pre-rice crop when rainfall accumulation reaches 100 mm/mo or as postrice crop using the receding rain and residual soil moisture.

· are acceptable crops because they are easy to prepare for consumption or to sell at the market.

· are drought-tolerant.

· are capable of using atmospheric nitrogen and contribute nitrogen to the soil. 

IMPORTANCE:

1. Intensifies land use and increases crop production per area per year.

2. Provides an additional source of food and income to farmers. Legumes can also provide biomass for green manure and fodder.

3. Sustains soil productivity through nitrogen cycling with legumes.

4. Weed production is reduced by planting an otherwise fallow area. 

DESIGNING THE CROP ROTATION PATTERN: (Refer to the figure on theoretical rainfall occurrence and proposed legume-rice sequences)

1. Based on knowledge from past years or from rainfall data, determine the onset and the end of the rainy season.

2. Choose short-maturing varieties of both rice and legume crop to accomodate a three-crop sequence or to avoid water stress.

3. Estimate the planting and harvesting dates of each crop in the cropping sequence.

4. If, based on the rainfall occurrence and drainage system, only a two-crop sequence is possible, there is a flexibility to choose a longer duration crop variety which has other desired characteristics.

Theoretical rainfall occurrence and the proposed legume-rice sequence

ADDITIONAL POINTERS:

1. The field should be well-drained. This minimizes flood damage if heavy rains occur during the legume cropping season and it facilitates post-rice land preparation for legumes.

2. If no legume crop will be grown after the rice crop, the field should still be plowed after rice harvest so that land preparation for the following pre-rice legume could be done quickly and easily using the early rains.

3. For the post-rice legume, a variety high in both grain and biomass yield (usually indeterminate or late-maturing) such as indeterminate cowpea, Indigofera, etc., is desirable so that more residues will be produced for use as fodder during summer or as green manure for the next crop. The crop should be tolerant to drought.

4. Other criteria in choosing crop varieties/species to be used are: adaptability to the site; marketability; tolerance to crop hazards -- like excess moisture (for pre-rice crop), drought (for post-rice crop), wind and short-term floods.

The ideal legume species are mung bean and cowpea. They are planted with 50 cm row spacing at a population of 300-350 and 350-400 thousand plants/ha as pre-rice and post-rice crop, respectively.

5. If the available time for pre-rice legume is less than 60 days, green manures, such as Sesbania, could be planted instead of grain legumes.

Rice ratooning

Ratooning, the ability of rice plants to regenerate new tillers after harvest, may be one practical way to increase rice production per unit area and per unit time. Because ratooned rice has shorter duration than a new crop, it may increase productivity in areas where cropping intensity is limited by inadequate irrigation facilities or by a second crop where the rice season is less than 180 days. Besides short duration, it costs less to grow a ratoon crop than a new crop. The major advantages of rice ratooning are:

· Lower production costs because of savings in land preparation and plant care during early growth;

· Short duration;

· Efficient use of the growing seasons, especially in monsoonal climates;

· Higher yield per unit area in less time;

· Possible maintenance of the genetic purity of a variety or hybrid rice through several seasons;

· Low irrigation water requirements;

· 60% reduction in the amount of water needed to compare to a second crop of transplanted rice; and

· 50-60% reduction in the amount of labor needed especially important considering the shortage of labor when the first rice crop is harvested and the second is planted. 

Yields are generally lower in a ratoon crop than in a transplanted second crop. However, the capital and labor savings are often enough to make a ratoon crop more profitable. The lower yield potential outputs of 3-4 T/ha have been frequently reported.

HOW TO HAVE RATOON CROP PRODUCTION:

Selecting the right variety is one of the most important and critical steps in obtaining high crop yields from ratoons. An ideal cultivar for rice ratoon cropping should have the following traits:

· Produces ratoon tillers after and not before harvest;

· Tillering from basal, not upper, nodes;

· Sixteen ratoon tillers/hill at 20 x 20 cm spacing;

· At least 3 leaves/tiller;

· Resistance to major disease and insects;

· Synchronized flowering and maturity;

· More than 60 growth duration from cutting to maturity; and

· High grain yield. 

Recommended land preparation practices for the main rice crop are undertaken only once because the ratoon crop does not require another round of land preparation. Deep plowing (25 cm depth) increases yield of the ratoon crop but under Philippine conditions, this is not practical.

Crop establishment in the main crop may either be by transplanting or direct seeding. Planting density is a more important factor in determining yield: the more plant/sq.m. the higher the yield (if no lodging occurs). Direct seeding usually results in a higher plant density than does transplanting at 20 cm x 20 cm distances but if the triple row transplanting method is used, plant density is about the same and less lodging occurs.

Fertilization of the main crop is essential for good yields in the ratoon crop. Deep placement of N fertilizer, if feasible, should be practiced as yields in the ratoon crop are increased by this practice. Green manuring practices and Nitrogen rates recommended for the first crop should be followed. N should be applied immediately at the harvest of the main crop to stimulate tillering of the ratoon crop. Suggested rate is 15-45 kg. N/ha.

Ratooning is a viable option for those farms where a second rice crop is not profitable and upland crops are either not profitable or cannot be grown due to poor drainage or other. factors.

Sorjan: towards rice-based integrated cropping systems

Sorjan, an indigenous technology of Indonesia, is a series of sinks or canals alternating with raised beds. Rice is usually planted in the sinks and a wide variety of upland crops is grown in the raised beds. The use of Sorjan (on 1000 sq.m) as one component of an integrated rice farming system results in higher and more regular income for the farmer due to the following:

1. Increased production per unit of land area 

2. Crop Diversification 

· Growing of high-value, off-season crops

· Simultaneous growing of a wide variety of lowland and upland crops assures farmers a good harvest from at least one of the crops.

· Increased fodder production for livestock. 

3. Earlier rice crops and higher yields in partially irrigated or rainfed areas

4. Other Benefits 

· Increase in quantity and variety of food available for home consumption

· Increased fertility of sinks

· More even use of labor throughout the year

· Practical and ideal for farmers whose land area is less than 1 hectare

· Could be adopted in a wide range of agro-ecological conditions. 

Note: This technology has a high labor requirement during the initial development of the plots.

1. INCREASED PRODUCTION AND LAND UTILIZATION

Production increases in Sorjan because water is used more efficiently, weed control is easier and both upland and lowland crops are grown in environments more closely tailored to their needs.

Water collects and stays in the sinks -- where it is needed most. The standing water aids rice growth and keeps weed populations to a minimum. The upland crops have a stable water supply (the standing water in the sinks which is available to them through wicking action), combined with good drainage and air circulation.

Along the sink portion (as well as in lateral canals) fish could also be introduced while, at the top portion of the sink, trellises for vegetable production are also recommended.

Under these Ideal conditions, production is very high. In work done by a Masteral student at U.P. Los Ba yields of grains and fodder from the Sorjan were 21 T/ha/yr of grains and 14 T/ha/yr of fodder for continuous cropping of rice.

2. DIVERSIFIED PRODUCTION

The growing of upland and lowland crops at the same time in the same field practically assures the farmer a good harvest of at least one of the crops. High-value crops, such as tomatoes and onions, fetch very high price when grown in the rainy season -- which is possible in Sorjan. The most profitable cropping pattern tested by IRRI was tomatoes -- onions -- bush sitao with a net income of more then P40,000/ha.

The quantity and quality of fodder production are also greatly increased. The addition of grain legumes, such as mung bean, provides high protein fodder for livestock. Intensive production of fodder grasses and trees to supplement livestock feeds is possible in this system. Napier planted in the side of the beds prevents the erosion of the beds (reducing maintenance) and produces more than 2 kg of high quality fodder grass/linear meter every month. In the UPLB study, fodder produced was enough to meet the feed needs of 11 carabao heifers or 29. cattle fatteners.

In the study conducted by IIRR in 1988 (dry season), data showed that the net income of rice planted on the sink portion yielded P9,471 on a hectarage basis, while on the elevated plot, cowpea had P10,773 and napier grass with P2,706.

Rice-fish also has very good potential in Sorjan due to the greater degree of water control. IRRI has recorded yields of nearly 200 kg of fish/ha/crop in addition to rice and upland crop yields. Yields could be tripled according to data from India.

3. EARLIER RICE CROPS WITH HIGHER YIELDS

In rainfed or partially irrigated areas, farmers must wait for enough water to accumulate before plowing and puddling the soil (land preparation). In Sorjan sinks where the rice is grown, water accumulation is faster because of runoff from the beds. Tests in India indicate that 46% of the rain falling on the beds is collected in the sinks. Fields can be puddled up to three weeks sooner. The same trials in India compared rice yields from Sorjan and normal rainfed rice over three years. Yields were 70% higher per unit area in Sorjan. This means that even by taking half the land out of rice production (i.e., the raised beds), yields were almost the same (1.5 T/ha for rainfed rice production and 1.3 T/ha in Sorjan).

BED CONSTRUCTION:

The construction of the beds can be done in several ways: plowing with an upland plow and shovelling the soil to form the beds; or plowing a flooded field, harrowing to move the soil into a rough bed and then shovelling to straighten the edges.

The method chosen will depend greatly on labor availability. An area of about 1,000 sq.m. requires anywhere from 300-600 man hours -- which can vary upon the number of beds to be constructed, their width and height.

DETERMINING BED HEIGHT AND WIDTH:

A number of factors need to be taken into consideration when deciding on bed height and width:

Height:

- Terrain. If field is sloping, a lower height is needed because there is less problem with drainage (for the upland crop planted on the beds).

- Chance of flooding/height of floodwater. If flooding occurs, the bed must be high enough so that the upland crops will not be flooded. 

- Rate of soil erosion from bed to sinks. Original heights of bed should be higher under high erosity conditions. 

- Soil fertility/depth of topsoil. Sinks should not be dug so deep that subsoil is exposed.

Width (and/or number of beds): 

- Water needs. If the land is rainfed, the width will be determined by how much runoff from the beds is needed for the rice in the sinks. 

- Convenience of the farmer. If the farmer plans to plow the beds, these need to be wide enough to facilitate the plowing operation. On the other hand, making many narrower beds is faster than making fewer but wider beds. 

INCREASING FERTILITY OF SINKS:

Removing topsoil from the sink area reduces soil fertility which will affect lowland crop yields. The farmer should therefore focus efforts on increasing soil fertility with large amounts of organic matter. Some possibilities include:

· planting green manure or grain legume in the sinks as soon as possible after formation

· mulching the crops with straw during the dry season

· moving livestock housing to sink areas during the dry season fallow period

· using Azolla if feasible (might be possible even in rainfed areas due to increased moisture availability and better water control). 

If moisture is present in the raised beds plant soybean, cowpea, or mung bean. Mung bean, in particular, does very well in newly constructed beds. Mulch the crop as well. Some upland crops are better suited than others to new Sorjan beds including sweet pepper, cucurbits (cucumber, squash and ampalaya) and grain and vegetable legumes.

SOURCE: PCARRD Monitor

A. for waterlogged areas

B. for predominantly rice-based areas

Maximizing the dry season for post-rice alternatives

RATIONALE:

There is a need to maximize the use of residual moisture an/or land area in rice-based farming systems, through crop-intensification by raising alternative crops after rice. This also contributes to the diversification of the farm.

Diversification of crops in a rice-based system, particularly with the use of vegetable crops, improves overall farm income, reduces the degree of deterioration of fertility, increases the uses of residual moisture and cropping intensity and improves daily cash flows. Such multiple cropping systems also help reduce insect populations.

CONSIDERATIONS:

· Is land efficiently used?

· Are all land areas utilized?

· Does the present use conserve the land?

· Is available water efficiently used?

· Are the crops grown when they are best suited?

· Is farm work designed to employ/utilize the labor of other family members?

· What capital resources are available?

Figure

IN THE SELECTION OF CROPS, CONSIDER THE FOLLOWING:

· market potential/demand
· price
· family benefit
· knowledge/skill in growing
· maturity of varieties
· time of planting
· method of planting

TRADITIONAL SYSTEMS:

1. Immediately before harvesting, mung bean seeds are broadcasted into the rice paddies. During harvesting, the mung beans are trampled thus establishing a mung bean crop stand.

Mung bean seeds are broadcasted

2. The rice stubble is cut to the ground and used as a mulch (in addition-to the rice straw from threshing). After mulching the field, the area is flooded for about 1/2 day or until it is saturated. The area is then planted with onion or garlic. (Nueva Ecija)

The rice stubble is cut to the ground

3. The field is plowed and harrowed and planted with various vegetables. (Nueva Ecija)

The field is plowed and harrowed

4. The paddies are cleaned of rice stubble, flooded until saturated and holes are dug at a 2 m x 2 m distance. Watermelon and musk melon are then planted. (Nueva Ecija and Cavite)

The paddies are cleaned of rice stubble

CROPPING PATTERN FOR A RAINFED LOWLAND RICE-BASED AREA: 

Rice is grown from July to October when water is available and the supply is adequate. Then, using residual soil moisture and available rain water, vegetable production can be feasible during the dry season.

CROPPING PATTERN FOR AN IRRIGATED LOWLAND RICE-BASED AREA:

Two crops of rice can be grown between May and January. The first with rain and the second with supplemental irrigation. Vegetable crops can then be grown during the dry months using available residual soil moisture.

Watermelons in rice paddies

RATIONALE:

Scarce land resources can be optimized and farm income can be increased by planting high value crops in rice paddies during the months following the rice harvest. Farmers in Cavite, Philippines, have demonstrated that planting watermelons can be a profitable venture if the activity is properly timed. Demand for watermelon is high, especially during the hot, summer months when it is a popular fruit used as dessert. The practice can also help farmers to recover any losses they might have suffered in their rice crop resulting from unforeseen circumstances like typhoons, pests and diseases, fluctuations in price and other causes. Labor inputs for crop establishment are low because minimum tillage is used, thus requiring little land preparation.

CONSIDERATIONS:

· Recommended Varieties

Cultivar	Maturity	Seed Rate/ha.
Sugar Baby	65 days	3-4 kgs.
La Mallorca	80 days	-do-

· Cropping Pattern

In order to receive the best price, watermelons should be planted from September to late October. Therefore, they should be planted 14-25 days before the rice crop is harvested. Planting during this period enables the farmer to harvest the crop earlier than most farmers, thus he can command a higher price for his produce. Also, raising watermelons during the cooler climate helps avoid possible thrips infestation which usually occurs during the hot, drier months of the year. Once the watermelons are harvested, batao (Dolichos lablab) can be sown as a cover crop and green manure for the remainder of the dry season.

Cropping Pattern 

· Land Preparation -- Direct seeding is a common practice in planting watermelons. 

a. Identify the rows where the watermelons will be planted.

b. Using a stick or planting board, push the rice plants to one side -- creating a space in which the planting can be done.

c. Dig the hole 20-25 cm deep and 20-25 cm wide. Place the topsoil one side of the hole and the subsoil on the other side. The holes are spaced 1.25 m between rows and 1 m between hills.

Push the rice plants to one side

The holes are spaced

· Planting

Mix equal amounts of compost or decomposed manure with the topsoil set aside earlier. Return the mixture to the hole. Sow 4-5 seeds. After the rice is harvested, thin out the unhealthy plants, leaving only three to mature. Place mulch around the base of the plant.

Place mulch around the base of the plant

Soil

What is Soil?

Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land – it is the “skin of the earth.” Soil is capable of supporting plant life and is vital to life on earth.

Soil, as formally defined in the Soil Science Society of America Glossary of Soil Science Terms, is:

1. The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.
2. The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time.

So then, what is dirt? Dirt is what gets on our clothes or under our fingernails. It is soil that is out of place in our world – whether tracked inside by shoes or on our clothes. Dirt is also soil that has lost the characteristics that give it the ability to support life – it is “dead.”

Soil performs many critical functions in almost any ecosystem (whether a farm, forest, prairie, marsh, or suburban watershed). There are seven general roles that soils play:

1. Soils serve as media for growth of all kinds of plants.
2. Soils modify the atmosphere by emitting and absorbing gases (carbon dioxide, methane, water vapor, and the like) and dust.
3. Soils provide habitat for animals that live in the soil (such as groundhogs and mice) to organisms (such as bacteria and fungi), that account for most of the living things on Earth.
4. Soils absorb, hold, release, alter, and purify most of the water in terrestrial systems.
5. Soils process recycled nutrients, including carbon, so that living things can use them over and over again.
6. Soils serve as engineering media for construction of foundations, roadbeds, dams and buildings, and preserve or destroy artifacts of human endeavors.
7.  Soils act as a living filter to clean water before it moves into an aquifer.

Soil Profile

There are different types of soil, each with its own set of characteristics. Dig down deep into any soil, and you’ll see that it is made of layers, or horizons (O, A, E, B, C, R). Put the horizons together, and they form a soil profile. Like a biography, each profile tells a story about the life of a soil. Most soils have three major horizons (A, B, C) and some have an organic horizon (O).

The horizons are:

O – (humus or organic) Mostly organic matter such as decomposing leaves. The O horizon is thin in some soils, thick in others, and not present at all in others.
A - (topsoil) Mostly minerals from parent material with organic matter incorporated. A good material for plants and other organisms to live.
E – (eluviated) Leached of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials – missing in some soils but often found in older soils and forest soils.
B – (subsoil) Rich in minerals that leached (moved down) from the A or E horizons and accumulated here.
C – (parent material) The deposit at Earth’s surface from which the soil developed.
R – (bedrock) A mass of rock such as granite, basalt, quartzite, limestone or sandstone that forms the parent material for some soils – if the bedrock is close enough to the surface to weather. This is not soil and is located under the C horizon.

Value of Soil

Social issues and soil quality

Nutrient cycling, water regulation, and other soil functions are normal process occurring in all ecosystems. From these functions come many benefits to humans, such as food production, water quality, and flood control, which have value economically or in improved quality of life. People can increase or decrease the value of soil benefits because land management choices affect soil functions. Thus, it is important to understand what benefits we derive from soil and their value so we can appreciate the importance of managing land in a way that maintains soil functions.

What are the social benefits of soil?

People tend to emphasize benefits with the most direct, private economic value. In rural areas, this is usually plant growth especially as  crops and rangeland, but also a recreation areas. In urban/suburban areas, the most direct economic benefits of soil relate to structural support for buildings, roads, and parking. Landscaping, gardening and parklands may also be valued economically.

Those are all on-site, short-term benefits. That is, the landowner who decides how to manage the soil also reaps the benefits (and costs) of those management decisions. In contrast, many important benefits are long-term or go beyond the land being managed. The landholders who make the management choices and pay the costs of managing land may not be the same people who are affected by the landholders decisions. Society should discuss the value of these off-site benefits and to what extent the land owner or society should pay to maintain these soil functions.

Public, off-site benefits of soil relate to the following resource issues:

Water quality of streams, lakes, oceans, and groundwater

Air quality, especially particulates

Greenhouses gases, including carbon dioxide, methane, and nitrous oxide

Biodiversity

Water flow and flood control

Sustainability and land productivity

Aesthetics

Summary of soil benefits

Soil Function	Benefit of Value to Humans
	On-site	Off-site
Nutrient cycling	Delivery of nutrients to plants Carbon storage improves a variety of soil functions	Enhances water and air quality Storage of N and C can reduce greenhouse gas emissions
Maintaining biodiversity and habitat	Supports the growth of crops, range land plants, and tress May increase resistance and resilience to stress  Reduces pesticide resistance	Helps maintain genetic diversity Supports wild species and reduces extinction rates Improves aesthetics of landscape
Water relations	Provides erosion control Allows on-site water recharge of streams and ponds Makes water available for plants and animals	Provides flood and sedimentation control Groundwater recharge
Filtering and buffering	Can maintain salts, metal and micronutrient levels within range tolerable to plants and animals	Improves water and air quality
Physical stability and support	Acts as a medium for plant growth  Supports buildings and roads	Nutrient Stores archaeological items Stores garbage
Multiple functions	Sustains productivity	Maintains or improves air and/or water quality

Low-external Input Rice Production - Chapter 3 - Pest/Weed Control

Major rice insect pests, their natural enemies and economic threshold levels

There are about 800 species of insects in the ricefields. Of these, about 100 species attack rice and the rest are all friendly insects. Out of the 100 pest species, only 7 are major pests in Philippine rice farms.

There is a new strategy of controlling these major pests in rice. This method is based on ecologically sound practices in reducing pest populations and is called Integrated Pest Management (IPM). IPM is a pest management system that, in the context of the associated environment and the population dynamics of the pest species, utilizes all suitable techniques and methods. This is done in a manner that maintains the pest population at levels below those causing economic injury.

By thoroughly understanding a given crop, its pests and other elements of the agroecosystem, IPM tries to maximize natural pest control factors and minimize the need for outside measures like chemical pesticides. IPM explicitly means:

· use of chemicals based on need

· utilization of economic threshold levels

· use of resistant varieties

· knowledge of cultural practices

· enhancement of biological agents

IPM can help farmers increase profits and reduce health hazards and pest outbreaks by maintaining the pest-natural enemy relationship in the field. In maintaining such relationships, insecticide use is "need-based". In practice, the farmer has to know the Economic Threshold Level (ETL) for a particular pest. ETL refers to the pest population level where control measures are needed.

The information in this paper is designed as a quick guide for identifying major pests of rice and their natural enemies and to help determine the economic threshold level for each pest.

RICE BUG (L. oratorius)

· ECONOMIC THRESHOLD LEVEL (ETL)

10 bugs in 20 hills

· SAMPLING METHOD

Sample early in the morning or late in the afternoon from 20 randomly chosen hills from flowering to hard dough stage. Sample twice a week.

· INSECTICIDE

Monocrotophos EC
Nuvacron USC

· DOSAGE (kg ai/ha)

0.4 each

· METHOD OF APPLICATION

Spray in the morning

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

WHORL MAGGOT (Hydrellia philippina)

· ECONOMIC THRESHOLD LEVEL (ETL)

a. 2 eggs/hill
b. 5% whorl maggot - damaged leaves + 5% leaves damaged by chewing insects at 5 DAT

· SAMPLING METHOD

20 random hills/ricefield at 5 and 8 days after transplanting

· INSECTICIDE

Monocrotophos EC

· DOSAGE (kg ai/ha)

0.4

· METHOD OF APPLICATION

Spray when threshold is reached

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

STEMBORER (Scirpophaga incertulas)

· ECONOMIC THRESHOLD LEVEL (ETL)

75 deadhearts in 20 hills or 2 adults or 2 egg-masses/m²

· SAMPLING METHOD

20 random hills/ricefield from tillering to panicle initiation stage

· INSECTICIDE

Chlorpyrifos EC

· DOSAGE (kg al/ha)

0.4

· METHOD OF APPLICATION

Spray when larva hatch

· DAMAGE

Larvae feed on leaves and leaf sheaths

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

GREEN LEAFHOPPER (N. Virescens)

· ECONOMIC THRESHOLD LEVEL (ETL)

1 hooper/tiller

· SAMPLING METHOD

20 random hills/ricefield 1 to 10 weeks after transplanting

· INSECTICIDE

BPMC WP

· DOSAGE (kg al/ha)

0.4

· METHOD OF APPLICATION

Spray when older nymphs are present

· DAMAGE

Drief leaf tips and leaf margins orange discoloration

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

CASEWORM (Nymphula depunctalis)

· ECONOMIC THRESHOLD LEVEL (ETL)

50% of the leaves are damaged. Combine the damage caused by other leaffeeding pests with that of caseworm.

· SAMPLING METHOD

20 random hills/ricefield at 2 to 6 weeks after transplanting

· INSECTICIDE

Carbaryl

· DOSAGE (kg al/ha)

0.5

· METHOD OF APPLICATION

Spot treatment

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

BROWN PLANTHOPPER (N. Lugens)

· ECONOMIC THRESHOLD LEVEL (ETL)

1 hopper/tiller

· SAMPLING METHOD

20 random hills/ricefield 2 to 10 weeks after transplanting

· INSECTICIDE

BPMC WP
Buprofesin WP

· DOSAGE (kg al/ha)

0.4 each

· METHOD OF APPLICATION

Spray when other nymphs are present.

NATURAL ENEMIES

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

LEAFFOLDER (Cnaphalocrosis medinalis)

· ECONOMIC THRESHOLD

LEVEL (ETL)

a. 15% of leaves are damaged before Panicle initiation.
b. 5% of leaves are damaged after panicle initiation stage.

· SAMPLING METHOD

20 random hills/ricefield at 2 to 6 weeks after transplanting watch for months

· INSECTICIDE

Monocrotophos EC

· DOSAGE (kg al/ha)

0.4

· METHOD OF APPLICATION

Spot treatment

Parasites

Predators

Pest

Host plants

Susceptible stage

Symptoms

CULTURAL MANAGEMENT PRACTICES FOR PEST CONTROL IN RICE

A cultural practice is any farm operation that will make the environment less favorable for pests to develop or multiply but which still favors rice production.

Rice ecosystems are fundamentally very stable systems but can be disrupted by inputs such as pesticides and inorganic fertilizers. There are few key pests in rice. Therefore, cultural practices, when used together with pest-resistant rice varieties, will provide adequate defense against most rice insects and diseases.

Cultural practices for rice pest management include the following:

SYNCHRONIZED PLANTING:

Since the massive introduction of rice intensification programs in the 1960s when shortduration modern rice varieties were introduced, there was room for planting rice three times a year or even five times in two years. Due to socioeconomic factors (labor shortages, market prices), staggered rice planting (i.e., non-synchronized) became unavoidable. This situation is ideal for continuous development of pests. Staggered planting with short idle intervals stimulates the build-up of BPH populations and may result in serious outbreaks of the rice dwarf virus, BPH, RTV (transmitted by GLH) and WBPH. Rice gall midge and the rice stink bug also became more serious in Indonesia because of staggered planting.

In staggered rice patterns, the generations of the pests are overlapping. There is no clear-cut fallow period (i.e., for soil preparation) between the two rice seasons. In this situation, any rice pest will build up continuously. On the other hand, in the synchronized patterns, there is a fallow period between the two rice seasons for about one month. This is the time for simultaneous soil preparation (irrigating field, deep plowing under the stubbles [ratoons] and sanitation). Most rice pests will then be destroyed.

CROP ROTATION AND INTERCROPPING (DIVERSITY):

Rotating rice with non-rice crops helps to break up the life cycle of both insects and pathogens. Continuous planting with no time for the soil to rest not only depletes its fertility but also enables pests to survive better. Intercropping (planting a second crop between rice, as in upland areas) will also reduce the spread of insects and diseases especially if the crop is very different in architecture from rice. During the growing of short maturity non-rice crops, there is no chance for rice pests to develop and they are gradually brought under control in areas where synchrony and crop rotation are strictly followed.

SANITATION:

Sanitation aims to remove all breeding or hibernating sites and sources of food of the insect or survival sites for the pathogen.

The survival stages of the rice stemborer, BPH and GLH in the ratoons are all destroyed by plowing under or burning stubble, ratoons and straw. Grasses on the dikes and surrounding areas may also be removed or cut short to disrupt the life cycles of stink bugs and the green leafhopper. In rice, intensive cultivation and wet weather do not permit drying and burning of the straw.

Straw burning is not always advisable because it destroys most of the arthropod populations that play an important role in decomposing plant remains. It also eliminates the available nitrogen in the plant remains. Nutrient loss by leaching is also much higher after burning.

When the rice plant is somewhat older, weed sanitation in the field is, of course, needed. Weedy fields may make the microclimate more favorable for insect pests than clean fields. Clean weeding may not be always advantageous for certain species of natural enemies because there may not be any shelter left for them. For example, spiders require some shelter to survive during the period between two rice crops and this may be provided by having weeds on the bunds. With respect to BPH, the sanitation program may be limited to only destroying the rice stubbles and ratoons because other grasses are not real host plants for the insect.

Fish and ducks have been successfully used in several countries to control sheath blight and insects/weeds, respectively.

FERTILIZER MANAGEMENT:

The population of many pests, such as certain aphid species, BPH, spider mites, blast, bacterial blight and sheath blight are significantly more abundant with increased nitrogen levels. The rice stemborer Chilo suppressalis and the gall midge have also been found to be significantly more abundant in fields treated with high rates of nitrogen. High nitrogen causes the rice plant canopy to become very thick. Although high nitrogen generally favors pests, it is not advisable to use fertilizers at lower than the recommended dosage, i.e., to sacrifice high yield for expected pest control. BPHresistant varieties have commonly been selected in high fertilizer environments and integrating such varieties with synchrony, rotation and other control tactics should achieve both high yield and BPH control. Unbalanced nutrients favor some diseases, e.g., low phosphate levels result in higher levels of brown spot disease.

WATER MANAGEMENT:

Water may influence the abundance of some pest species. BPH problems are known to increase when irrigated rice cultivation replaced dry rice cultivation. In Japan, insects are abundant in the humid lowlands and rice fields with standing water have been found to encourage the multiplication of BPH. In Indonesia, BPH prefers irrigated rice to upland rice. The problems are more serious in plots continuously flooded or with standing water. The green leafhopper Nephotettix virescens also seems to favor fields with stagnant water and specially those with intermittent rain as well.

Good water management should therefore help control certain rice pests. Draining the fields for about two days suppressed BPH outbreaks in Malaysia. In the Philippines, farmers withhold irrigation and plants are spread apart every few rows to help dry out the fields for BPH control. To effectively control the rice water weevil, fields are drained at the proper time and irrigation is stopped for a predetermined period. Draining the water level in rice fields destroys the eggs of BPH laid in the leaf sheaths. Deep irrigation in the morning followed by the addition of a certain amount of kerosene to water gives good control of BPH. In Indonesia, it is a common practice to raise the irrigation water level to control BPH; sand or sawdust containing 0.25 l kerosene for every 100 m is then broadcast on the raised water level and the plants are shaken.

PLANT SPACING:

The spacing of rice plants in a field is believed to influence the abundance of certain rice pests. Close spacing may rapidly increase the BPH population. Close spacing results in a more shaded, cooler and more humid microenvironment, which makes it less favorable for the development of the natural enemies of BPH. Both GLH and WBPH may also increase in closely spaced rice plants. In direct-seeded rice where spacing is much closer than transplanted rice, these pests may become more severe. Close spacing also intensifies the severity of rice diseases such as sheath blight.

Spacing should be such that it allows some sunshine to penetrate into the basal portions of the rice plants. Solar and ultraviolet radiation restrain BPH increase. More air flow also makes the micro environment less humid and may also help the natural enemies develop. The distance between rice plants depends on the variety. Modern rice varieties with high tillering capacity may be planted further apart than those with less or moderate tillering capacity. Common spacing between rice plants is 20 x 20 cm or 25 x 20 cm.

KEY:

BPH -- Brown Planthopper
GLH -- Green Leafhopper
WBPH -- White-backed Planthopper
SB -- Stemborer
ShB -- Sheath Blight

Pesticide poisoning

The most common routes of pesticide poisoning are:

Breathing into the lungs

Skin contact

1. Skin contact -- by spilling or splashing pesticides on clothes or directly on skin. Dry materials can also be absorbed.

Wrists, armpits, neck, groin and feet are areas of the body that absorb pesticides more quickly than others. Cuts and scrapes also allow more pesticide to enter more easily.

2. Breathing into the lungs -- Dusts, sprays or fumes can enter the system by being breathed into the lungs. Poor ventilation indoor allows greater exposure.

3. Oral/Swallowing -- Pesticides are absorbed well through the mouth, stomach and intestine. Pesticides can be accidentally taken in by people who eat or smoke while applying pesticides or when improperly stored in food containers.

4. Eye contact -- Pesticides absorption and local damage can occur with eye contamination.

FIRST AID:

In Case of Skin Contact with Pesticide

1. Take off any contaminated clothing.

2. Wash skin with lots of soap and water. 

Do Not Touch the Pesticide Again or Handle Contaminated Clothing.

In Case of Eye Contact with Pesticide

1. Hold eyelids open and wash with gentle stream of cool, clean, free-flowing water.

2. If with contact lenses, remove them,

3. Continue rinsing eyes for at least 15 minutes.

4. See physician. 

In Case of Breathing in (Inhalation of) a Pesticide

1. Remove person from exposure to pesticide.

2. If conscious, place person in a sitting position with head and shoulders elevated.

3. If unconscious, give artificial respiration and call for medical assistance. 

In Case of Oral Contact or Swallowing a Pesticide

A. Induction of vomiting only if

1. patient is conscious

2. pesticide is moderately to extremely toxic. 

Induce vomiting using the following procedure

1. Sit or stand-up patient.

2. Give 1 to 2 glasses of water.

3. Tickle back of the patient's throat using a bland instrument (spoon handle). Use 2 fingers of the other hand to force the patient's cheek between his teeth.

4. Return patient to lying position-turned towards the left, neck extended. 

General Management

1. Keep patient calm and at rest.

2. Keep close observation of breathing and state of consciousness.

3. Place patient in proper position.

3.1 Place patient on his left side with head lower than the rest of the body by 15 to 30 degrees.

3.2 Keep patient comfortable but not hot and sweating or cold and chilly. Maintain a normal temperature. 

BREATHING:

If Breathing Stops

1. Pull chin forward to avoid tongue dropping to back of throat.

2. Roll patient on his back, keeping chin pulled forward and head back. Remove any vomitus or secretions from the mouth using a clean cloth.

3. Pinch patient's nose and blow into his mouth through a piece of cloth or handkerchief following your normal breathing rate. Alternatively, close his mouth and blow into his nose.

Make sure patient's chest is expanding with each flow. Continue until normal breathing takes place.

If Convulsion Occurs

· Insert padded gag between the teeth to prevent the patient from biting his tongue.

· Prevent further injury by placing a cushion or pad under his head and prevent him from falling. 

Tips to Induce Vomiting

4 egg whites for children 

8 egg whites for adults.

Efficient and safe use of pesticides

Pesticides are still widely used pest control agents against a variety of pests in rice. There are specific pesticide groups which control specific pest problems. There are insecticides to control insects, herbicides for weeds, fungicides for fungi, rodenticides for rodents, etc.

Despite their popularity, improper and careless usage of pesticides has resulted to undesirable effects on people, livestock, non-target organisms and the environment in the rice field. Accidents have also resulted during their use, transport and storage.

To avoid these adverse effects, the following tips should be followed in using pesticides:

THINGS TO REMEMBER BEFORE MIXING:

1. Read the label carefully. The label contains necessary information relevant on how the product must be used and what to do in case of poisoning.

Read the label carefully

THINGS TO REMEMBER DURING MIXING:

1. Wear gloves, safety glasses and/or masks/respirators and mix pesticides outside the house.

2. When mixing liquid concentrates with water, it is always advisable to place pesticide into the sprayer tank first before mixing with water.

Caution: If acid is used, it must be poured into the water during the preparation of the solution. Do not pour water into the acid because an explosion could result.

3. Immediately after mixing, close pesticide container tightly and keep it in a safe area not easily reached by small children.

THINGS TO REMEMBER DURING APPLICATION: 

1. Never smoke or eat during the spraying operation.

2. Wear protective clothing, such as long-sleeved shirts, pants and respirators when spraying.

Never smoke or eat during the spraying operation

3. Spray pesticide diagonal to the direction of the wind not against it.

4. Do not spray during windy days.

5. Limit spray application to 3 to 4 hours only.

Do not spray during windy days

THINGS TO REMEMBER AFTER APPLICATION:

1. Wash all exposed body parts twice with soap and water; a bath would be more advisable. An alkaline soap (Perla) should be used in taking a bath, stay away from sources of drinking water.

2. Wash all contaminated clothings thoroughly with soap and plenty of water. Separate them from ordinary family laundry.

3. Do not dispose excess pesticides nor wash the sprayers in waterways (irrigation, canals, streams, rivers). Do not burn containers.

4. Dispose empty pesticide containers by burying them in suitable pits that prevent pesticide leakage into the groundwater or other bodies of water. Never burn paper packages and plastics.

Wash all exposed body parts

Low-cost control methods for golden snails (kuhol)

INTRODUCTION:

The golden snail, commonly known as kuhol (Pomacea caniculata), was originally introduced in the Philippines as a source of protein for the family. However, it has become one of the most destructive pests of lowland rice. Kuhol usually feeds on the succulent parts of the rice plant, causing stunted growth and eventual destruction of the rice plant.

Kuhol belongs to the snail family (Pelidae) that lives only in or close to fresh water in swamps and rivers in South America. When kuhol was commercially introduced into the Philippines, its possible escape was not anticipated. The natural predators of the kuhol in South America do not exist in the Philippines. Therefore, there has been no natural check against growth and reproduction.

Between 25-500 eggs, depending on breeder size, are laid in oval-shaped clusters. Eggs are laid early in the morning and evening on standing crops, along dikes and on any object sticking up above the water surface. One kuhol can produce up to 200-300 eggs/week or 1,000-1,200 eggs/month, with 80% hatchability.

Kuhol can breathe underwater like fish or in the open air. When ricefields are drained, kuhol burrows into the moist mud, digging deeper as the dry season progresses. It can sleep hidden in dry soil for over 6 months then awaken overnight when the soil is flooded.

The kuhol is a voracious plant eater. It feeds on a wide range of plants such as Azolla, duck weed, water hyacinth, rice seedlings and other succulent leafy plants and vegetables. In irrigated ricefields, the rice is most vulnerable to the kuhol during the first 2 weeks of establishment for transplanted rice and during the first 4 weeks for direct-seeded rice.

To save the rice plant from this pest, farmers tend to use commercial/chemical snail killers which are not only hazardous to human, fish and animal health, but also alter the environment and add to the farmers' expenses. Some of the chemicals used to control snails have recently been banned. (Integrated Kuhol Management, DA/FAD, 1989).

DIFFERENT CONTROL STRATEGIES FOR KUHOL:

A. BEFORE TRANSPLANTING RICE

1. Several weeks before transplanting, allow ducks to roam around the paddy field. Ducks will feed on the eggs and smaller snails.

Allow ducks to roam around the paddy field

2. Hand-pick all the larger snails not eaten by the ducks. Crush them with a mortar end pestle and feed them to the ducks. The snail meet end shells are excellent sources of protein and calcium for laying ducks.

Hand-pick all the larger snails

B. AFTER TRANSPLANTING RICE

1. Install a wire mesh screen in the water runways to prevent the eggs and adult snails from entering the paddy field during irrigation.*

Install a wire mesh screen

2. Maintain shallow water (2-3 cm) during the first 15 days after transplanting to minimize damage. One month after transplanting, allow ducks to roam the paddy field and consume the remaining eggs and snails.

Maintain shallow water

3. Construct depressed strips in the paddy where wafer will be retained when the field is drained. The snails will migrate and collect in these lateral depressions and can then be collected.

Construct depressed strips

C. PLACEMENT OF STAKES

1. Snails prefer to climb above the water level to lay their eggs.

2. Collect stakes 0.5-0.75 m long and 2 cm in diameter. Arrange them 0.5 m from the rice paddy dikes, 2-4 m apart The kuhol will lay their eggs on these stakes.

Collect stakes 0.5-0.75 m long

3. Gather the eggs, crush them and feed them to ducks, chickens and pigs.

Gather the eggs and feed them to ducks, chickens and pigs

D. RICE HULL

1. Separate coarse hulls from the fine ones with a sieve.

2. After a rain, evenly spread a 1-2 cm layer of rice hulls in the ricefield. The hulls will affect the digestive system of the snails, causing them to starve and die. Three or four days after spreading the hulls, collect the dead snails.

Separate hulls

Spread hulls

E. EAT KUHOL

The kuhol first introduced as a high protein food for human consumption, has a high nutritive value. A bite-size snail contains the following:

Food energy	83.0 calories
Protein	12.2 gm
Fat	0.4 gm
Carbohydrates	5.5 gm
Ash	3.2
Phosphorous	61.0 mg
Sodium	0.4 mg
Potassium	17.0 mg
Riboflavin	12.0 mg
Niacin	1.8 mg

The kuhol also contains vitamin C, zinc, copper, manganese, magnesium and iodine. (Integrated Kuhol Management, DA/FAD, 1989).

RECIPES:

TORTANG KUHOL

1 saucer cooked ground kuhol

1 tbsp. chopped onion leaves

1 tbsp. chopped tomatoes

1 tbsp. chopped onions

1 tbsp. crushed garlic

2 tbsp. cooking oil

1/2 tsp. salt

1 whole egg beaten

1 tbsp. all-purpose flour 

Put salt on kuhol then saute with garlic, onions and tomatoes. Remove from pan and mix sauted ingredients with beaten egg. Coat the mixture with flour and fry. Serve hot.

GINATAANG KUHOL

2 saucers cooked kuhol shelled

2 cups coconut milk

1 tbsp. crushed garlic

1 tbsp. chopped onions

1 tbsp. chopped tomatoes

1 pc. ginger

2 tbsp. achuete

2 tbsp. cooking oil 

Saute garlic, ginger, onions and tomatoes in hot cooking oil. Add cooked kuhol to sauted mixture. Stir in coconut milk and achuete. Boil until oil comes out. Serve hot.

Note: Snails should not be eaten by humans or livestock including ducks if collected from rice paddies which have been sprayed with chemicals.

Easy ''do-it-yourself'' snail collector

Golden snail (Pomacea caniculata), a serious rice pest, can now be locally controlled at a bargain by using a do-it-yourself method of scoop and scrape snail collecting device called salaan collector.

Instead of bending or- stooping hundred of times to collect snails, the multipurpose snail picker, with its long handle, can now reach distant crawling snails and clusters of eggs, without tiresome bending.

With this simple and inexpensive picker, one can collect and dispatch snails by the thousands while they are still in egg clusters. This device, with its scorpion-shaped plate attachment, enables one to scrape eggs from walls and host plants without damaging them.

A. Snail collecting

B. Scraping eggs on walls

C. Scraping eggs on plants

HOW TO MAKE A "SALAAN" SNAIL COLLECTOR

Materials Needed:

1 pc 1 in x 1 in x 6 ft wood or bamboo pole

1 pc 2 1/2 in x 3 1/2 in gauge 20 or 22 galvanized sheet (This is roof gutter sheet gauge)

1 pc 1-2 mm mesh coconut strainer (salaan)

3 pcs 1/8 in x 3/4 in length self tapping screw

3 pcs 1/8 in x 1/2 in cap screw 

Procedure:

1. Paste the pattern below onto gauge 22 sheet metal.

2. Cut sheet metal with snip.

3. Drill hole with 1/8 in diameter puncher.

4. Bend metal to shape.

5. Plane sharp edges of 1 in x 1 in x 6 ft wood to make round for greater comfort.

6. Screw salaan with wood handle.

7. Assemble finished scorpion-shaped plate into salaan.

Note: For the scorpion plate, tin can materials may be used although life span of the plate

will be shorter.

How to make a "salaan" snail collector

Makabuhay, a natural pesticide for lowland rice

RESEARCH FINDINGS SHOW THAT:

· The application of chopped Makabahay is as effective as the use of chemical pesticides in reducing deadhearts and white heads due to striped stemborer attack and in reducing the green and brown leafhopper populations.

· The aqueous extract of Makabuhay (50 9/125 ml water) is toxic to green leafhopper when applied to rice seedlings by root-soaking 24 hrs before transplanting or by spraying it to the seedlings. These treatments are comparable to root-soaking in chemical pesticides.

· The submerged chopped Makabuhay stem is toxic to the rice green leafhopper.

· The combination of aqueous Makabuhay extract root soaking and broadcasting of chopped vine is as effective as the recommended chemical pesticide seedling treatment followed by spraying with chemical pesticides 25 days after transplanting.

· Broadcasting of ground Makabuhay vine (0.25 kg/sq.m) on rice seedbed 10 days after sowing is as effective as broadcasting with chemical pesticides.

Sc. Name: Tinospora rumphii Local Names: Makabuhay (Tag., Bik., Ilk.); Manunggal (Ilonggo); Abukay (Ilk.). Palayawan (Waray) 

PREPARATION AND USAGE:

Root soaking

1. Chop the vine into small pieces and pound it with the use of a mortar and pestle.

2. Add 1 liter water for every 200 9 crushed Makabuhay vine. Thoroughly stir the mixture, then soak the rice seedlings overnight before transplanting.

Ten to 15 kg of chopped vine are sufficient to treat seedlings needed to plant 1 hectare. 

IMMERSION 

1. Cut the Makabuhay vines to approximately 1 ft lengths.

2. Tie both ends of the cut vines onto bamboo stakes as shown in the diagram.

3. Drive the stakes into the ground along water inlets.

4. You can also put 1 liter chopped Makabuhay vines inside a fish net bag and place the bag along the wafer inlets. Replace the Makabuhay every 2 weeks. Check the bag regularly for accumulation of mud or other debris.

Tie both ends of the cut vines

Put 1 liter chopped Makabuhay vines inside a fish net bag

Low-cost insect trap

The light trap is an inexpensive tool used in monitoring insect pest populations and helping reduce their numbers. Light traps were used by many farmers before the introduction of modern rice varieties when chemical pesticides were still not generally available. The light trap can also be used in fishponds or rice- fish paddies to attract insects upon which the fish can feed. As pesticides became more common and were used to prevent damage to crop, light traps became less important.

Today, however, chemical pesticides are recommended only as a last resort because of their high environmental, health and economic costs. Therefore, pest management practices today require a greater knowledge in pest identification and a system of monitoring insect populations.

LANTERN DESIGNS:

Lanterns can easily be made from locally available materials like empty glass jars (mayonnaise jars) as illustrated below. The lantern costs from P50 (design A) to P15 (design C). It uses about P1 to P2 worth of kerosene per night and produces a bright white light.

Lantern designs

LOCATING THE INSECT TRAP:

The lantern is attached to a frame (tripod) of either bamboo or wood and is hanged above the rice crop. The frame has a platform that supports a basin of water just below the lantern. Adding some cooking oil to the water can make the insects immobile upon falling into the water.

In rice-fish fields, hang the lantern over the water in the trench at a height which is just above the dike. At that height, the light is easily seen by insects flying just above the crop canopy.

Locating the insect trap

USING THE LANTERN:

The lantern should be lit as soon as it gets dark (when insects are most attracted to light) for 24 hours. In cases where the field is far from the house, the lantern should be filled with just enough kerosene to burn for 2 hours. The lantern should be visited daily and the insects identified and counted.

NOTE:

· If the light trap is primarily intended to reduce the insect population, more than one trap is advisable.

· If the light trap is intended to monitor insect population for forecasting, 1-2 traps/ha. is enough. Check with the local technician.

Pests	Local Name	Time When Most Attracted
Scarab beetle	Uwang, salagubang, salaginto	New moon
Cricket (Gryllotalpa orientalis)	Subong	Full moon
Caseworm (Nymphula depunctalis)	Paruparong gabi	New moon
Green semliooper (Naranga aenescens)	Paruparong gabi (berdeng uod)	New moon
(Rivula atimeta)	Mabalahibong berdeng uod	New moon
Gallmidge (Orseolia oryzae)		Full moon
Armyworm (Mythimma separate)		New moon
Cutworm (Spodoptera litura)
(Spodoptera mauritia)
Stemborers:
Striped (Chilo suppressalis)
Yellow (Scirpophaga incertulas)	Aksip	New moon
Pink (Sesamia inferers)
White (Scirpophaga innotata)
Brown planthopper (Nilaparvata lugers)	Ngusong kabayo	Full moon
Whitebacked planthopper (Sogatella furcifera)
Green leafhopper (Nephotettix virescens)
(Nephotettix nigropictus)	Berdeng ngusong kabayo	Full moon
(Nephotettix malayanus)

The above is compiled from researches conducted by the Entomology Department of IRRI, Los Ba Laguna, Philippines.

Weed management

Weed management

REASONS FOR WEED MANAGEMENT:

1. Weeds reduce yield by competing with the crop for sunlight, moisture and soil nutrients.

2. Fertilizer application in weedy fields may prove wasteful because weeds absorb the fertilizer (especially N) more effectively than the crop.

3. Weeds may serve as alternate hosts for crop pests. 

LOW-COST WEED MANAGEMENT PRACTICES:

There are many ways to manage weeds in ricelands at little cost without having to resort to the use of herbicides. The key to low-cost weed management and high yield is prevention. Preventing weeds from growing is cheaper and easier than removing them. Some simple methods of prevention include: (1) thorough land preparation; (2) using weed-free seed or seedlings; (3) employing shade and mulch to slow down weed growth; (4) crop rotation; and (5) good water management (for lowland rice).

1. Land preparation. Good land preparation gives the crop a chance to grow ahead of the weeds. This reduces competition during the very sensitive seedling stage. Moreover, by the time the weeds start to emerge, the plants have grown tall enough to shade them out, further preventing their growth.

2. Weed-free seed and seedlings. If planting material is not kept free of weeds (or weed seeds) then the crop will have a competitor from the start of growth. In the Philippines, transplanting weeds with rice seedlings is causing losses of 16-23%. (See technology sheets on Rice Seed Production.)

3. Shading/mulching. "Let plants do the work for you." Keep a cover of economic plants on the field to shade out weeds.

· Select taller varieties of the crop to be grown.

· Increase the planting density to reduce weed competition.

· Use Azolla to effectively shade out grasses, sedges and small broadleaf weeds in (lowland rice). Use of Azolla alone can reduce weed dry matter production by 50-60%.

· Residues from the previous crop can be applied as mulch to deter weed growth (aside from conserving water and improving soil fertility).

· In fallow periods, a good stand of green manure will shade out most weeds, preventing them from setting seed.

Select taller varieties of the crop

Increase the planting density

4. Crop rotation can considerably reduce weeds. Weed population is lower when planting rice after an upland crop like mung bean or cowpea rather than when it is preceded by another rice crop. The radical differences in cultural practices between upland and lowland crops result in different species of weeds with each system. By rotating crops, weeds have less chance to establish, keeping their population down.

With continuous monocropping, weeds associated with the crop have a chance to establish themselves and increase their populations.

In areas where crop rotation cannot be practiced, levels of weed control have in the first crop affect weed population in the second. Good weed control in the first crop means fewer weeds in the second.

Another way to inexpensively control weeds is to have livestock do it for you. Both ducks and fish consume large numbers of weeds.

Most crops do not have to be kept weed-free for the duration of their growth, especially so when labor is scarce or expensive. The number of weedings can be reduced by comparing the recommended weed-free period and the time that critical competition begins between the crop and the weeds. This varies with crops and different cultural methods. For example, transplanted rice is supposed to be kept weed-free for the first 30-days after planting. However, the period when weed competition will actually reduce yields does not begin until 25-30 days after transplanting, so weeding can be reduced to one time only, that time between 20-30 days after transplanting.

Weed free period in rice crop

WEEDS ARE NOT ALWAYS BAD FOR FARMERS:

· Some weeds can be used as additional forage for livestock.

· Other weeds can be returned to the soil to increase OM.

· Allowing weeds to grow in some paddy dikes provides shelter to many beneficial insects where they stay throughout the dry season and help keep pest populations down once rice planting begins.

Weed control in lowland rice

With no weed control measures, an average of 34% yield loss is expected in transplanted lowland rice and 45% in direct-seeded rainfed lowland rice.

COMMON WEED CONTROL METHODS:

· Land preparation
· Hand weeding
· Mechanical weeding (use of push-type rotary weeders)
· Flooding (keeping the field flooded for a period of time to control most weeds)
· Use of herbicides
· Use of azolla

General comparison of selected weed control measures

MECHANICAL WEEDER VS. PRE-EMERGENCE WEEDICIDES

If on-farm labor is unavailable and must be hired, the use of mechanical weeders will involved higher costs compared to the use of weedicides. However, the net returns will be higher if farm family labor is used to utilize mechanical weeders.

The following case study (based on farm records) compares the two methods:

	Weeder	Pre-Emergence Herbicide
1. Area planted	1/2 ha.	1/2 ha.
2. Variety	IR 42	IR 42
3. Crop period/duration	Aug. 4	Nov. 18,1987
4. # Cavans harvested @50 kg/cay.	42	38
5. Gross Value of harvest @P3.5/kg	P7,350	P6,650
6. Cost
a. Labor for marking rows for transplanting @P40/ha.	20	20
b. Depreciation cost of weeder*	50	-
c. Cost of 1/41iterweedicide (Machete)	-	50
d. Labor for mechanical weeding (5 man days @P35)	175	-
e. Labor for spraying	-	8.75
(1/4 man days @P35)
f. Additional handweeding (2 man days @P35)	70	70
g. Total cost of weed control	P315.00	P148.75
7.Gross returns less cost of weed control	P7,035.00	P6,501.25

Above case also illustrates that a more effective weed control scheme is one that involves a combination of two or more weed control methods.

* Assuming a weeder costs P300 and can last for six cropping seasons.

Water management for weed control in rice

Flooding rice paddies was one of the first tools developed by farmers to control weeds in rice. On farms with reliable irrigation, water. management is also one of the most effective and lowest cost methods of controlling weeds. Even for farms in rainfed or semi-irrigated areas where the need to conserve water limits the ability to manipulate water levels, water management is still an important tool in weed control.

Water management for weed control in rice

1. At land preparation

Keep the paddy field flooded after harrowing to kill weeds and to hasten decomposition. Water level should be high enough to submerge all weeds.

2. At final levelling

Final levelling eliminates any high spots in the field. Weed seeds in these high spots would be able to germinate because they would be above the water level.

In areas with good irrigation, final levelling should be done in saturated soil but with no standing water.

In rainfed or semi-irrigated areas, conserve water by maintaining water levels at 3 cm.

Final levelling should be done 1 day before transplanting.

3. At transplanting

Irrigated: The puddled, levelled field should not have standing water. This facilitates straight-line transplanting because the lines can easily be seen and assures that the seedlings will establish good root-soil contact and quickly begin to grow.

Rainfed: Paddies should be drained to facilitate transplanting unless no rain is expected -- in which case some water should be maintained in the paddies.

4. Transplanting to tillering

Paddies should be flooded 1-3 days after transplanting to prevent weed seeds from germinating. The time to flood is determined by presence or absence of Azolla (Flood 1 day after transplanting if Azolla is being used.) and establishment of the seedlings.

Water level should be 2 cm initially and increased gradually to 10 cm as the rice plants grow.

5. After maximum tillering to post-flowering

Once maximum tillering stage is over, weeds have no effect on rice yield. Continuous flooding or submergence of the field is desirable but not necessary. Water depth may vary from 3-10 cm if there is sufficient irrigation water. Where irrigation water is scarce, the objective should be to maintain at least a saturated soil once crop canopy is full enough to shade out weeds.

Using ducks for low-cost weed management

The use of ducks can complement other weed management practices in rice paddies where straight row planting is used. When the crop reaches 20 cm in height (approximately 25 days after transplanting) until the booting stage, the ducks can be allowed into the rice paddy without damaging the crop. Forty to fifty (40-50) adult ducks feeding for 3 hours a day for 3 consecutive days can weed a 1,000 sq.m area. Any species can be used but Mallard ducks (Anas platyrhynchos) are most recommended because they are more active and have light and narrow bodies.

PROCEDURE

1. Irrigate the field to a depth of 3 cm (ducks will not enter the rice paddy field without water). To encourage them to enter, broadcast a handful of rough rice into the paddy.

Irrigate the field

2. The constant dabbling or feeding and trampling by the web-footed ducks make the soil soft and muddy and inhibit the growth of weeds and at the same time incorporate weeds growing in between the rows of rice.

Dabbling

3. Broadleaf weeds and sedges are eaten by the ducks. Insects (e.g. moths or stemborers, hoppers, mole crickets, etc.) and golden snails which are found at the base of the rice crop are also eaten, thereby reducing pest populations.