potato 5-9-12 CLEAN - Vegetableipmasia.org

ORGANIC POTATO PRODUCTION Table 15.1 Pesticides Labeled for Management of Colorado Potato Beetle Class of Compounds Product Name (active ingredient) Product Rate PHI (days) REI (hours) Efficacy Comments OILS Cedar Gard (cedar oil) Glacial Spray Fluid (mineral oil) surface area 1 qt/A -­‐ -­‐ ? 25(b) pesticide. 0.75-­‐1 gal/100g Up to day of harvest 4 ? See label for specific application volumes. For beetle larvae only. Golden Pest Spray Oil (soybean oil) 2 gal/A -­‐ 4 ? Only for use against larvae. 59B PHI = pre-­‐harvest interval, REI = restricted entry interval. -­‐ = pre-­‐harvest interval isn't specified on label. Efficacy: 1-­‐ effective in half or more of recent university trials, 2-­‐ effective in less than half of recent university trials, 3-­‐not effective in any known trials, ?-­‐ not reviewed or no research available 15.2 Aphids, primarily the green peach aphid, Myzus persicae; Potato Aphid, Macrosiphum euphorbiae; MelonAphid, Aphis gossypii; Buckthorn Aphid, Aphidula rhamni; and Foxglove Aphid, Aulacorthum solaniTime for concern: June through vine-killKey characteristics: Adults of the potato infesting aphid species are approximately 1/25 to 2/25 inch in length and vary incolor from yellow to black. They may be winged or wingless. In the fall, winged aphids are produced and mate. The eggs areblack and less than 1/50 inch in length. See Cornell aphid fact sheet (Reference 101), Hmelon aphid fact sheet (Reference 102)and University of Maine aphid photos (Reference 103).Relative Risk: Aphids are rarely a problem on organic farms due to the higher numbers of parasites and predators, but theycan transmit viruses, which will affect yield of potatoes and other crops susceptible to viruses. Virus infection is more seriousfor growers who save their own seed.Management Option Scouting/thresholds Recommendation for Aphids Early detection of migrant aphids is extremely important to seed growers who must minimize spread of potato leafroll virus and other aphid-­‐vectored virus diseases in their fields. Yellow sticky traps and tape are useful in determining initial arrival of winged aphids and their seasonal presence/absence. Plant damage from feeding by aphids is often subtle and seldom reflected, at least in the early stages, by obvious changes in plant growth, growth form, or foliage color. Large populations may be detected by the appearance of cast skins, sooty mold, or shiny honeydew accumulations on lower foliage and the soil. Put up either yellow sticky traps or water-­‐pan traps. Traps should be examined twice a week and the number of winged aphids recorded and removed. A total catch of ten aphids per trap over a seven day period is an alert to the possible need for application of an insecticide. When the number of aphids per trap increases, examine one fully expanded leaf from each of five different plants in different rows at each of ten sites per field. Count all of the aphids. Apply insecticide when the following action threshold is reached. UPLANT GROWTH STAGE Before tuber initiation Tuber initiation 1 to 2 weeks before vine kill Within 2 weeks of vine kill UACTION THRESHOLD 100 aphids/50 leaves 200 aphids/50 leaves 500 aphids/50 leaves In addition, seed potato growers may consider applying stylet oil to hinder virus transmission by aphids (see Section 12.17: Virus Diseases). 642012