Small grain yields can be lowered by diseases, insects, and weeds. Careful monitoring of fields to identify pest problems early can help prevent economic losses. This guide will help scouts and growers know when to look for major pests and how to scout for them. No pesticide recommendations are included. Refer to the current issue of Extension's Small Grain Production Guide and the North Carolina Agricultural Chemicals Manual or contact local Extension Service agents for specific pesticide recommendations.
 

1 Small Grain Pest Management


 

Integrated Pest Management

    What is integrated pest management (IPM), and how can it help me produce a profitable small grain crop? These are logical questions often asked by growers. Integrated pest management is a systematic way of controlling pests that combines tried-and-true pest control methods with new approaches. The objective of IPM is to help growers produce crops more profitably. To do this, IPM will (1) use all proven methods of lowering pest levels (rather than relying solely on chemicals), (2) use pesticides according to need, and (3) help growers consider all aspects of pesticide use.
    Pests can lower crop yield and quality and reduce profits. Less obvious, but just as important, is that profits also may be lost when money is spent unnecessarily to control pests. To avoid unnecessary expenses, growers must determine pest levels in each field and compare the potential damage to die cost of control. The economic threshold is that point where the predicted cost of pest damage to a crop is higher than the cost of treatment for the pest.
    IPM is designed to help growers protect their crops at the lowest possible cost. A successful IPM program has two elements:

1. The crop is checked or scouted regularly and systematically to search for, identify, and count pests.
2. Decisions about pesticide applications and other control measures are based on scouting results and economic thresholds for each pest population. Pest populations must reach a certain level, the economic threshold, before the cost of control measures is justified.
    If no economic threshold has been established for a pest or if chemical applications must be used preventively, then the pesticide used should be carefully matched to the pest and the situation and all efforts made to time the application correctly. Regular scouting for these pests should still be used to evaluate control efforts.
 

Scouting

    The purpose of field scouting is to detect the presence and concentration of pests. Scouting is not a casual or spontaneous procedure. Small grains must be checked regularly using methods described in this manual. The information gathered while scouting can be used to help make immediate pest control decisions. Scouting observations may also become part of a field history that can be used to make pest control decisions in the coming years.
    An important aspect of scouting is identifying pests accurately. Lumping insects into a general category such as worms or identifying weeds only as grasses is not adequate. Knowing precisely which insect, weed, or disease is present in a field is important to making management plans. When control decisions are made on the basis of accurate information, a waste" "shotgun" approach to control can be replaced with a specific treatment plan.
    Avoid the temptation to make pest control decisions for all fields based on information from only one or two fields. Pest levels can vary greatly from one field to another, even though the fields appear similar. Each field should be scouted closely according to the schedule prescribed in this manual.
 

Economic Thresholds

    It seems logical to think that if pests are present they must be damaging the crop or interfering with its growth, thus causing a yield loss. Actually, in some cases, pests can be in the crop for weeks before it pays to control them. For example, plants may simply outgrow a low level of insects. Another point to consider is that nature has ways of working against an increase in pests (through natural predators or diseases, for example). In other words, the presence of a pest in a field does not necessarily mean that the pest population will ever reach damaging levels. Treating for a pest that will not reduce the quality or yield of the crop is a waste of money. It may also cause unwanted residues and increase the possibility of off-site problems. IPM saves money by helping to determine if there are enough pests to warrant treating the crop.
    Keep in mind that although the thresholds given in this manual have worked very well, they were developed as guidelines for average conditions. In unusual situations, such as periods of drought stress or when multiple pests are present, thresholds may have to be altered. Consult an experienced advisor when such situations occur.
 

Pesticide Selection and Application

    Once a pest exceeds the economic threshold, it is necessary to determine the best and least expensive way to prevent unacceptable losses. If treatment is needed, the pesticide and its rate and method of application must be customized to the pest. Making these decisions carefully is probably the surest way to save money. High pesticide rates are not needed if the correct pesticide is chosen and the method of application delivers the right amount of chemical to the pest. For pesticides to be applied properly and efficiently, the sprayer pressure and volume must be correct; die right nozzle type, arrangement, and number must be used; and the sprayer must be accurately calibrated. Pesticides may cause other pests, called secondary pests, to increase and require treatment. This treadmill effect, where one application of pesticide causes the need for another, must be avoided.
    Specific pesticide recommendations are not included in this guide. When deciding on a pesticide, talk to your county Extension Service agent and consult the North Carolina Agricultural Chemicals Manual before talking to your chemical supplier.
 

Responsible Use of Pesticides

    Pesticides have become an important tool in producing crops. But like any tool, they can be overused and misused. New rules concerning registration of pesticides, public concern, cost, environmental contamination, water resource degradation, and a host of other issues require that all growers reexamine their pesticide use. Responsible use of pesticides will help ensure that growers continue to have access to these tools.
 

Pesticides and Water Quality

    Pesticides have been found in groundwater in many states, including North Carolina. There is good evidence that this situation can be avoided if a few precautions are taken when loading and using pesticides.
    One of the most likely locations for off-site movement of pesticides is at the loading station. This location is often near a residence and close to the wellhead because it is convenient. During the season small amounts of pesticide are spilled. After a number of growing seasons, pesticide begins to accumulate in the soil. The natural chemical and biological systems that normally neutralize pesticides are overwhelmed. Rain moves these chemicals down through the soil. If there is enough pesticide and enough rain, groundwater may be permanently contaminated. This situation is even worse if the well is improperly cased, the case is cracked, or die well is shallow (less than 50 feet).
    This situation is easily avoided. Mixing and loading stations should be a minimum of 150 feet from a wellhead. A concrete pad should be constructed so that spilled pesticides can be collected for proper disposal.
    Many farms are close to surface water, including rivers, streams, and lakes. These resources are valuable and should be protected from pesticide contamination. There are two primary ways that pesticides move off site: by spray drift and runoff with rain water.
    Spray drift is difficult to control because wind can carry a pesticide a great distance before depositing it. Small grain spraying is especially susceptible to this problem since high pressure is often used. Obviously this situation can be avoided by spraying when it is calm. But often the wind continues to blow even when pesticide applications are necessary. This is a difficult situation and there are no sure solutions. Consider spraying fields that are not close to water or that have a hedge row or some other buffer. Then try to spray the fields next to water resources early or late in the day when the wind is calmest. Reduce spray pressure to the lowest setting possible. This will decrease the number of small droplets that are easily moved by the wind. A conscientious effort by growers to reduce drift will greatly reduce the chance of water resource pollution.
    Pesticide runoff with rainwater may be the primary way pesticides move off site. As little as 0. 1 inch of rain can wash pesticides off plants. This can cause two problems. First, it removes pesticides from the target plant and leaves it unprotected. Second, the pesticide may contaminate nearby water. The easiest solution to these problems is not to use a pesticide just before rain is expected. However, this strategy presents two more problems. First, summer thunderstorms are hard to predict. However, many growers are familiar with the patterns of rainfall on their farm and are pretty good at figuring out where it is going to rain, if it rains. Use this knowledge to avoid spraying just before a rain. Second, some pesticides, such as preemergence herbicides, require rainfall to be effective. Of course, too much rain will reduce the effectiveness of these materials. Avoid application just before anticipated rains of I inch or more. Doing this will allow the pesticide to be incorporated and will lessen the likelihood of off-site movement.
 

Pesticides and Wildlife

    Wildlife is an important and valued resource for all citizens and should be protected as much as possible. Wildlife can be affected both directly and indirectly by pesticides. When an organism is directly exposed to a pesticide - when a bird eats a granule of pesticide, for example - the direct effects of such exposure include death, weakening, or behavior change. An organism is indirectly affected by a pesticide when its habitat or food source is removed. This can happen when herbicides kill plants that are vital to an organism's habitat or when an animal eats prey that has consumed a pesticide. Using the least toxic material possible will also help minimize the toxic effects of pesticide use on wildlife. Look at die LD50 for any pesticide that is being considered. Generally the more toxic the material (the lower the LD50) the more likely it is to affect wildlife.   If there is a choice among pesticides, choose the one with the highest LD50. Reducing drift and off-site movement of pesticides will also lower the possibility of affecting nontarget species and help preserve our rich wildlife heritage.
 

Pesticides and Food Safety

    There are concerns that residues in small grains may present a health hazard to consumers. Although scientific evidence does not support this contention, the perception is enough to deter some consumers. The best way to avoid potential problems is to minimize pesticide use and use pesticides properly (at the correct rate and timing). This will assure potential buyers that small grains are the safest possible.

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