Rice Production: Chapter 11 - Pest prevention

Introduction

Irrigated rice must be protected against serious damage from permanent or sporadic pests. In many developing regions, the tendency is to rely on control of pests (through chemical pesticides), rather than on prevention of pests (through management practices). It is Up to the extension agent to make the farmer aware that pest control in its broadest sense includes everything that makes life difficult for the pest, kills it, discourages it from reproducing, or prevents it from spreading. This chapter describes some of the management practices which can help prevent pest infestation from reaching the stage where the far met will be forced to resort to chemical control.

I. Educating the Farmer

Farmers field school

The key to effective pest prevention lies in a complete and accurate understanding of the pest, its life cycle and habits. Although most farmers will usually be able to identify the pest causing damage to their crops, often they lack a detailed knowledge of the relationship between the pest and the rice growth cycle. This is hardly surprising, since most pest activity occurs at night, or in places in which it is difficult to observe (e.g. inside the stern of the plant).

Perhaps the most important contribution the extension agent can make toward pest prevention is to educate the farmer about the life cycle and habits of the pest. Teach the farmer to look for signs of crop damage. Point out as many pests as you are able to identify, and explain as much as you know about their life cycles. Ask questions which will start the farmer thinking regularly about pests.

II. Preventative Practices/Insects

Field study and identifying of insects

With one or two exceptions, it is difficult to eliminate insect pests completely simply with management practices -but there is no question that preventative practices can have a significant effect in controlling or reducing insect populations. And since crop damage occurs in direct proportion to insect population, it is important to know which management practices will help keep down the numbers of harmful insects. Preventative practices which have been effective in Sierra Leone include:

a) Flooding

Flooding

After the harvest, many species of insect pests enter into the pupating, or resting stage. Flooding the plots immediately after harvest can drown many pupating insects, especially stem borers. Flooding also effectively controls air-breathing insects, such as the mole cricket.

b) Draining

Draining

Draining the plots represents an easy, inexpensive, and effective control against caseworm. Encourage the farmer to drain the affected plot(s) dry for 7-10 days to prevent the spread of caseworm. (Note: be sure not to drain the water out of one plot and into another, since this will merely result in the spread of the infestation.)

c ) Burning

Burning off rice straw

Burning off straw and stubble after the harvest drives away any regaining insects, kills pupating insects in the soil, arid helps control disease as well.

Hand weeding in the rice paddles

d) Plawing

Removal of paddy stubbles and wild grasses after harvest by plowing them under will minimize the next generation of insect pests by killing larvae hibernating in the soil and eliminating a ratoon crop (which serves as a host environment for rice-specific pests).

e) Brushing Bunds and Peripheries

Many species of insect pest emerge from the plots during certain farming operations (e.g. brushing, burning, plowing) and seek refuge in the weeds growing on the bunds and along the edges of the swamp. Brushing the bunds and peripheries deprives many insects of a valuable habitat and can significantly reduce their numbers. 

f) Crop Rotation.

Crop Rotation.

Crop rotation can be extremely effective against certain insects, especially rice bugs. In a heavily pest infested area, encourage as many farmers as possible to plant a rice pest resistant crop (e.g. groundnuts or cowpeas). If deprived of a rice environment, many rice specific insects will move elsewhere or die. 

g) Uniformity of Planting

If sufficient labor is available, encourage the farmer to plant the entire crop at one time. Since the entire crop will subsequently undergrow the same growth stages at the same time, certain pests which attack only during certain growth stages (e.g. rice bag) will have a very short attack "window."

h) Host Plant Resistance

No rice variety has been found to be immune from insect attack, but certain varieties clearly are more susceptible to attack by certain insects. Teach the farmer to be aware of such susceptibilities (most farmers will in turn be able to teach you about such things). Advise against the continued use of varieties which local insects seem to prefer.

Rice birds

III. Preventative Practices/Birds birds represent the single greatest pest hazard to rice farmers in Sierra Leone. Bird attack during the final stages of grain ripening can cause losses of up to 90% in uguarded stands - in a matter of days. Most farmers are well aware of the bird problem and rely on traditional methods of prevention and control. These include bird-scaring apparati constructed of sticks, vines, tin cans filled with pebbles, rags etc...), slings, and snares.

Note: Some farmers attempt to poison birds by baiting them with rice treated with pesticide. Needless to say, this practice i extremely dangerous, all the more so because people have been known to eat the birds killed by the poisoned bait. Always discourage this practice, which in any case affects only a few birds.

IV. Preventative Practices/Rats

Catching Marsh rice rat

Rats also can pose a major pest problem - and they can be extremely difficult to control. Two types of rat arc common in Sierra Leone The cutting grass is a large nocturnal animal (weighing up to 40 labs) which causes extensive damage to rice by feeding on the bases of the culms. Although many farmers believe that cutting grass will not cross broad irrigation channels or enter into flooded plots, the animal in fact is an excellent swimmer. Maintaining 6"-8" of standing water on the plots will slightly discourage feeding, but the only effective control is to fence off the swamp and deny the animal entry, or hart it antoher rice pest is the smaller field rat (actually several different species). These 8"-10" animals live in nests constructed inside the bunds and attack the rice during all growth stages. They are extremely difficult to control as they make their homes inside the swamp itself. The most effective way to control their numbers is to tear apart the bands and destroy the nests.