Insect Management in Cereals

Once fields are properly scouted, data can be used to determine insect control options. Course of action should be started only when you are fully armed with up-to-date, accurate information writes Thomas Kipkorir

Proper crop rotation with alternate crops is an essential practice in any crop production to reduce buildup of insects, weeds and diseases. Insect attacks do not always result in economic injury, so certain insect management practices can be used to ensure cost-effective control decisions.

Scouting for insects.
Depending on location and when the crop is planted, insect problems vary from nonexistent to severe. Identifying the pest and understanding its potential for damage is necessary when selecting appropriate control methods. Each pest does not respond the same way to a given method. Monitor fields at least twice per week. Walk a “V” or “W” pattern through the field and select plants from 12 random locations along the pattern. When plants are still small (up to 10 leaves), examine 6 adjacent plants per location for insects and disease. As plants get larger sample 3 leaves per plant on 6 adjacent plants per location (total of 216 leaves).

Insects cause injury to the leaves, stems, roots, and fruit. The developmental stage of the plant at the time of attack often governs which plant part different insect pests may injure. However, some insects feed specifically on one plant structure; others may feed on several structures. The first step in control is to identify the insect.

Certain cultural practices may have a dramatic effect on the potential for economic injury by certain insects. Planting during optimal growing conditions ensures rapid seedling emergence and subsequent growth. This reduces the amount of time that plants are susceptible to injury from seedling insect pests.

Most insect problems can be treated as needed if detected early, but no one insecticide will adequately control all the insects that may attack a crop. Scouting for insects is the most efficient way to determine what problems may exist and what action should be taken.

Preventive treatments may be necessary for certain insect pests. Preventive treatments are used against insects that are certain to cause economic injury if they are present. Field history, harvest dates and insect pressure in nearby production areas influence preventive measures decisions.

In addition to monitoring for pest insects, some beneficial species exist which should be considered. Several species of predatory and parasitic insects are present in crops. These natural controls are considered especially during early season. Big – eyed bugs, minute pirate bugs, fire ants and Cotesia wasps are four important beneficial insects. The presence of these natural controls may delay the need to treat for bollworms. The use of beneficial insects should be maximized in attempts to reduce production costs.

Decision to apply an insecticide should be based on scouting and the use of threshold. Scheduled or automatic applications of insecticides should be avoided because unnecessary application can be more costly than just the cost of the insecticide. Application of insecticides on an as-needed basis will allow beneficial insects to be preserved which reduces the likelihood of secondary pest out breaks.

Resistance Management
In a population of resistant insects, insecticide resistance levels to a particular class of insecticide increase each time that class of insecticide is used. Once a material is used, its level of effectiveness will likely be reduced against subsequent generations within the season.

Therefore, alternating the use of insecticide classes on different generations of insects during the season is a highly recommended resistance management tactic. Since most insect pests are highly mobile, such a strategy will be most effective if adopted by all farmers in a large geographic area.

Pesticide precautions

• Observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
• Store all pesticides in original containers with labels intact and behind locked doors. Keep pesticides out of reach of children.
• Use pesticides at correct label dosage and intervals to avoid illegal residues or injury to plants and animals.
• Apply pesticides carefully to avoid drift or contamination of non – target areas.
• Surplus pesticides and containers should be disposed of in accordance with label instructions so contamination of water and other hazards will not result.
• Follow directions on the pesticide label regarding restrictions as required by Laws and Regulations.
• Always dispose pesticide containers by burning and burying and not throwing away in water bodies or garbage dumps.

Scouting for insect pest is important for two reasons. Yearly scouting helps you build an on-farm database that can be used to select appropriate insect management tactics for future crops. Scouting also helps you determine if and when to spray insecticides. Once fields are properly scouted, data can be used to determine insect control options. Course of action should be started only when you are fully armed with up to date, accurate information.