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Impact Report
| For plan | Insect Pest Management of New Mexico Crops |
| Date | February 28, 2008, 6:43 pm |
| For Objective | Short-term Show short-term objectives |
| Impact Report | USDA /Aphis released a number of parasitoids of alfalfa weevil in the 1980s, but their success in controlling alfalfa weevil since then was unknown. We have determined that three species are established in New Mexico. Two species are responsible for virtually all of the biological control of alfalfa weevil in southern New Mexico. We have determined that Oomyzus incertus is responsible for approximately half of the control of alfalfa weevil in the Mesilla Valley. O. incertus and Bathyplectes spp. togeather often produce 70-80% control . In the Pecos Valley, on the other hand, O. incertus is very rare and control of alfalfa weevil is highly variable. The success of O. incertus in the Mesilla Valley suggests that it could be successful in the Pecos Valley as well. Having a similar level of control in the Pecos Valley would save growers in the Pecos Valley over $600,000 per year. We have determined that crop microclimate can have a dramatic effect on survival of insect pests in cotton and pecan in southern New Mexico. High temperatures and low relative humidity in the crop canopy produces extremely high mortality in some insects eg. boll weevil, and similar, albeit less dramatic, effects on other insects. Row spacing, row orientation, N rates, plant population irrigation timing and plant architecture can affect crop microclimate and insect mortality. However some management decisions that dramatically reduced boll weevil survival have less effect on Ledipopterous pests. Changes in row orientation and row spacing for example do not have enough impact on leopidopterous pests to justify use in pest management recommendations. Yield partitioning and compensation testing in cotton indicate that bollworm is rarely an economic pest in New Mexico. Late season bolls, which are those typically injured, have low value, primarily due to low natural retention, producing few bolls /acre on the later nodes. Also, compensation testing indicates that cotton can compensate for very high losses of squares late season by retaining bolls that could otherwise have been shed, and to a lesser extent, by increasing boll size of those retained. Compensation data is also being used in conjunction additional data from Drs. Bundy and Ellington to develop an economic injury level for Lygus in New Mexico. Field trials were conducted on commercial farms to determine how much impact alfalfa has on predation in pecan and cotton. The data in cotton suggests that our initial theory based on data from other states may not be appropriate for New Mexico. Data collected the last two years suggests that cotton in the Pecos Valley at least, depends on relatively constant immigration of predators from hay rather than periodic sudden influxes at cutting. If this holds true then hay is critically important for pest control in cotton and pecan in the Pecos Valley. Hay: Assuming conservatively just 1 application on 50% on the Pecos Valley acres and that we could reduce applications by only 75% (less than other states have accomplished), we would save over $600,000 in the Pecos Valley alone. Similar results in other counties in NM would easily put savings over 1 Million per year. This also does not take into account additional cost savings from a reduction in secondary pests that had population increases due to the early season application and its impact on beneficial arthropod populations. Cotton: Our data suggests that insecticide applications for square injury by bollworm could be almost eliminated in southern New Mexico. However realistically many applications are made for insurance against risk, fear of loss and under pressure from sales representatives. A 50% reduction of insecticide applications on non transgenic cotton is ambitious but achievable. Reducing inputs will help in retention of cotton as a rotation crop in the Pecos Valley, and would be the most important impact Pecan: Our primary impact on pecan will be to avoid losses in yield from insect pests particularly as the landscape changes to a more monoculture environment favoring more insect pest outbreaks. Our strategy is to determine how to use smaller acreage of alfalfa to maintain populations of beneficial arthropods in pecan |