11. RISK OF PESTS IN PEANUT, INTEGRATED PEST MANAGEMENT, AND PESTICIDE STEWARDSHIP

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1 11. RISK OF PESTS IN PEANUT, INTEGRATED PEST MANAGEMENT, AND PESTICIDE STEWARDSHIP David L. Jordan Extension Specialist Crop and Soil Sciences Barbara B. Shew Extension Specialist Plant Pathology and Entomology Rick L. Brandenburg Extension Specialist Plant Pathology and Entomology Greg Buol Research Technician Crop and Soil Sciences Gail Wilkerson Professor Crop and Soil Sciences RISK MANAGEMENT Managing pest risk in peanut can be complicated and is very important to maintaining a successful and sustainable peanut production system. A pest risk management tool has been developed at North Carolina State University to help peanut farmers and those who advise them. This tool allows users to determine if the production plan they have developed is effective across all pest disciplines. A plan designed to control a pathogen and prevent disease might increase incidence of another diseasecausing pathogen or insect. Farmers, Extension agents, consultants, and others in the agricultural sector are encouraged to try the peanut risk tool as they develop management strategies for the 2019 peanut crop. Step 1. Access the risk tool at the following website: Step 2. Select North Carolina and then Go if you want to use the tool without having an account (Figure 11-1). If you want the ability to save field plans and make changes during future visits, create an account and use the login option. Step 3. Input data in all sections on the left side of the screen (Figure 11-2). Step 4. The number of red, yellow, or green dots on the right side of the screen indicates the risk level to yield you are taking with the pest management practices you have decided to use Peanut Information

2 Figure Peanut risk management tool access screen. Figure Data entry screen Peanut Information 173

3 Step 5. If needed, change practices to minimize risk, but keep in mind that risk of other pests can be affected and that production costs will also change. Step 6. Remember the risk tool is for planning prior to the season. Almost all farmers start with a plan but need to make adjustments based on weather, pest outbreaks, and economic constraints. This risk tool was created to help farmers start the season by selecting practices that minimize pest risk and identify pests that might impact peanut yield during the season. The risk tool is currently being updated to reflect new varieties, production and pest management practices, and to include a weed management category. Please contact your local county Extension agent or specialists if you have questions. INTEGRATED PEST MANAGEMENT (IPM) Integrating pest management strategies is important in protecting yield from pests. The Southern IPM Center ( defines IPM in the following manner: Integrated pest management (IPM) is socially acceptable, environmentally responsible, and economically practical crop protection. Traditionally, a pest is defined as any organism that interferes with the production of the crop. We generally think of pests as insects, diseases, and weeds, but there are many other types, including nematodes, arthropods other than insects, and vertebrates. We now also deal with pests in many non-crop situations, such as human health and comfort. The Southern IPM Center also suggests the following approach to protecting peanut and other crops from pest injury by using the PAMS approach (Prevention, Avoidance, Monitoring, Suppression): Adoption of integrated pest management (IPM) systems normally occurs along a continuum from largely reliant on prophylactic control measures and pesticides to multiple-strategy biologically intensive approaches and is not usually an either/ or situation. It is important to note that the practice of IPM is site-specific in nature, with individual tactics determined by the particular crop/pest/environment scenario. Where appropriate, each site should have in place a management strategy for Prevention, Avoidance, Monitoring, and Suppression of pest populations (the PAMS approach). In order to qualify as IPM practitioners, growers should be utilizing tactics in at least three of the four PAMS components. The rationale for requiring only three of the four strategies is that success in prevention strategies will often make either avoidance or suppression strategies unnecessary. Prevention is the practice of keeping a pest population from infesting a field or site and should be the first line of defense. It includes such tactics as using pest-free seeds and transplants, preventing weeds from reproducing, irrigation Peanut Information

4 scheduling to avoid situations conducive to disease development, cleaning tillage and harvesting equipment between fields or operations, using field sanitation procedures, and eliminating alternate hosts or sites for insect pests and disease organisms. Avoidance may be practiced when pest populations exist in a field or site but the impact of the pest on the crop can be avoided through some cultural practice. Examples of avoidance tactics include crop rotation such that the crop of choice is not a host for the pest, choosing cultivars with genetic resistance to pests, using trap crops or pheromone traps, choosing cultivars with maturity dates that may allow harvest before pest populations develop, fertilization programs to promote rapid crop development, and simply not planting certain areas of fields where pest populations are likely to cause crop failure. Some tactics for prevention and avoidance strategies may overlap in most systems. Monitoring and proper identification of pests through surveys or scouting programs, including trapping, weather monitoring and soil testing where appropriate, should be performed as the basis for suppression activities. Records should be kept of pest incidence and distribution for each field or site. Such records form the basis for crop rotation selection, economic thresholds, and suppressive actions. Suppression of pest populations may become necessary to avoid economic loss if prevention and avoidance tactics are not successful. Suppressive tactics may include cultural practices such as narrow row spacing or optimized in-row plant populations, alternative tillage approaches such as no-till or strip till systems, cover crops or mulches, or using crops with allelopathic potential in the rotation. Physical suppression tactics may include cultivation or mowing for weed control, baited or pheromone traps for certain insects, and temperature management or exclusion devices for insect and disease management. Biological controls, including mating disruption for insects, should be considered as alternatives to conventional pesticides, especially where long-term control of an especially troublesome pest species can be obtained. Where naturally occurring biological controls exist, effort should be made to conserve these valuable tools. Chemical pesticides are important in IPM programs, and some use will remain necessary. However, pesticides should be applied as a last resort in suppression systems using the following sound management approach: 1. The cost benefit should be confirmed prior to use (using economic thresholds where available); 2. Pesticides should be selected based on least negative effects on environment and human health in addition to efficacy and economics; 3. Where economically and technically feasible, precision agriculture or other appropriate new technology should be utilized to limit pesticide use to areas where pests actually exist or are reasonably expected; 2019 Peanut Information 175

5 4. Sprayers or other application devices should be calibrated prior to use and occasionally during the use season; 5. Chemicals with the same mode of action should not be used continuously on the same field in order to avoid resistance development; and 6. Vegetative buffers should be used to minimize chemical movement to surface water. PESTICIDE STEWARDSHIP Avoiding Spray Drift Integrated pest management does not exclude pesticide use, but it does encourage a holistic approach and careful consideration of whether a pesticide is the best approach and the most economical approach. In most cases, pesticides deliver a much greater economic return than the costs of the pesticide when an economicallyimportant pest is present or when there is a high likelihood that a pest will be present in the crop. Pesticide stewardship is very important in peanut production systems. Farmers make as many as 15 applications in a year to suppress pests and protect peanut yield and quality. Adhering to worker protection standards and being well informed on when to apply pesticides at the appropriate rate and timing are essential in protecting people, animals, and plants from injury and maximizing yield and profit. Recent challenges with stewardship with auxin technology in cotton and soybean remind us of how difficult it can be to make sure pesticides go only where they are needed. While most pesticides applied in peanut are not volatile and will not move from fields due to vapor drift, particle drift remains a major concern. The principles discussed in the auxin-training program administered jointly by the NC Cooperative Extension service (Alan York) and the NCDA&CS (Patrick Jones) and designed to reduce particle drift should be used in peanut. Physical spray drift can be minimized by paying close attention to the following factors: Nozzle type. Nozzles that deliver coarser droplets that move toward the ground more quickly than finer droplets will reduce physical drift of spray solution. Most peanut farmers apply pesticides with either regular flat-fan nozzles or hollow-cone nozzles. These nozzles are often very effective in delivering spray solution of fungicides, herbicides, and insecticides onto and through the canopy. However, the fines, or small droplets associated with these nozzles, are particularly sensitive to physical drift. When possible, use coarser-textured nozzles. Research is underway at NC State to determine efficacy of commonly used pesticides used in peanut when applied with nozzles that deliver droplets that are larger and less prone to physical drift than regular flat-fan or hollow-cone nozzles. Pesticides with systemic activity do not require as much coverage of peanut foliage (control of insects and fungal pathogens) Peanut Information

6 or weeds to be effective. However, contact herbicides (Gramoxone and other formulations, PPO-inhibiting herbicides, and Basagran) and fungicides that are not absorbed and translocated throughout leaf tissue are generally more effective when applied in higher spray volumes and when spray droplets are smaller and distributed uniformly throughout the canopy. Until more information is available, these pesticides should be applied using flat-fan or hollow-cone nozzles that deliver smaller droplets and ensure effective distribution throughout most of the peanut canopy or weed. Wind speed and direction. The higher the wind speed is, the further spray droplets will travel before they reach the ground, top of peanut canopy, or weeds. Avoid spraying when wind speed is high. The maximum wind speed for auxin herbicides applied in cotton and soybean is 10 miles per hour. This would be a good maximum, although sprays delivered through regular flat-fan or hollow-cone nozzles will travel further in lower speed winds than the spray delivered through very coarse nozzles required for Enlist and Xtend crops. Applying pesticides when wind speed is less than 3 miles per hour increases the likelihood of thermal inversions and makes it difficult to know which direction the wind is blowing. Be keenly aware of the ramifications of off-site movement with respect to the areas around peanut fields. Spray pressure. The relationship between spray pressure and nozzle type is clearly established. Higher pressure creates a higher percentage of fine droplets that can remain suspended in the air and subsequently move with the wind. Some pesticides do not require high pressure, but often late-season fungicides require high pressure to get the spray solution into the middle and bottom of the canopy to protect peanut from leaf spot disease or to get solution to the base of the plant to control stem rot and Sclerotinia blight. Spray volume. Using higher spray volumes often allows use of coarser droplets without sacrificing coverage. Coarser droplets create a lower percentage of fines, which reduces off-site movement. However, applying pesticides in higher volumes decreases efficiency of spraying operations, although contact herbicides and fungicides can be more effective because coverage increases when applied in a higher spray volume. Sprayer speed. Higher sprayer speeds increase off-site movement of pesticides. At higher speeds, the boom height is less predictable depending on the roughness and contour of the field, and greater turbulence can occur behind the sprayer when traveling at higher speeds. Greater turbulence results in a longer period when spray droplets are suspended. This longer suspension time can increase the likelihood of off-site movement of pesticides. Boom height. The higher the boom and spray nozzles are above the target pest or crop, the longer the time that spray droplets are suspended. This longer suspension time increases the risk of particle drift. The contour of a field can result in the boom height being too high or too low Peanut Information 177

7 Co-application of pesticides and adjuvants. Spray solution characteristics can vary depending on how products interact in the tank, and these changes can result in greater likelihood of physical drift or volatility, depending upon the mixture components. Pesticides as Resources Pesticides are important resources used in peanut and are essential to maintaining yield and quality and generating economic return by farmers. Preventing injury to workers and the public, keeping pesticides within field boundaries, and using them in a coordinated effort with cultural practices to suppress pests will increase the sustainability of pesticides in peanut production systems. It is also important to practice resistance management for all groups of pesticides: fungicides, herbicides, and insecticides. Resistance of more than one species within a pest discipline (entomology, plant pathology, weed science) exists in North Carolina, and there are concerns that the number of cases is increasing. Maintaining the availability of pesticide tools will require proactive management, persistent monitoring, and changing specific pesticides when needed. There are many sources of information relative to pesticide modes of action and managing resistance. Refer to chapters in Peanut Information related to management of disease, insects, and weeds for specific details on developing a comprehensive management strategy for pests in peanut Peanut Information