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2022 Midwest Vegetable Guide

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Potato – Diseases 238 Midwest Veg Guide 2022 through drip irrigation under unperforated plastic beds. Before planting, allow product to dissipate for 1 week for every 10 gals. per acre plus 1 more week. REI: 5-day. IRAC 08F, FRAC M03, HRAC NC. RUP. Velum Prime (4.16SC) (fluopyram) | 6.5-6.84 fl .oz. per acre. Apply through overhead chemigation. Do not exceed 13.7 fl. oz. per acre per season. Allow 5 days between applications. REI: 12-hour. PHI: 7-day. FRAC 07. Vydate C-LV (3.77WSL) (oxamyl) | 34-68 fl. oz. per acre. Apply as a banded or shank-injected at-plant in-furrow soil treatment incorporated 2-4 inches deep with at least 20 gals. water per acre, or overhead chemigate to deliver rate in 0.5 inch of irrigation water. Do not exceed 8 applications or 306 fl. oz. per acre per season. In Kansas, allow 14 days between applications and do not exceed 4 applications or 204 fl. oz. per acre per season. REI: 48-hour. PHI: 7-day. IRAC 01A. RUP. Ring Rot of Potatoes - Clavibacter Bacteria The ring rot bacterium is easily spread. Although this bacterium will not survive more than 1 year in the soil (and thus can be controlled by crop rotation), a farm with ring rot must conduct a thorough clean-up before bringing in seed for the next crop. The organism can easily survive the winter in crop debris or soil on storage walls; seed cutters, bin pilers, graders, and other handling equipment; tractors, fork lifts and other vehicles; and on burlap sacks, wooden boxes, or other containers. If clean seed potatoes contact any of these contamination sources, the problem can recur. Non-Pesticide Use certified disease-free seed. When cutting seed stock, the cutter should be periodically cleaned and disinfected, especially when changing seed lots. The first step is to clean all contaminated surfaces with hot soapy water under pressure or steam to remove all soil and debris. Then apply a disinfectant sanitizer. For more information about sanitation, see Commercial Greenhouse and Nursery Production: Sanitation for Disease and Pest Management (Purdue Extension publication HO-250-W), available from the Education Store, . Scab of Potatoes - Streptomyces Bacteria Scab is more common on potatoes grown in soils with pH over 5.2. Non-Pesticide Avoid fields with a history of nematodes, Fusarium or Verticillium wilts, droughty, wet, or compacted soils, and other conditions (such as insufficient nitrogen) that might add undue stress to the crop and increase susceptibility scab. Acidify soil to a pH between 5.0 and 5.2 with elemental sulfur in the fall prior to planting. Silver Scurf of Potatoes - Helminthosporium Fungus Use a fungicide when appropriate. Non-Pesticide Plant seed pieces certified to be free of disease. Harvest potatoes as soon after maturity as possible. Rotation to a non- host crop 2-3 years. Pesticide azoxystrobin products (azoxystrobin) | Use 2 lb. a.i. per gallon formulations (Quadris) at 0.4-0.8 fl. oz. per 1,000 row feet. Use 3.3 lb. per gallon formulations (Azteroid) at 0.24- 0.48 fl. oz. per 1,000 row feet. Use 0.83 lb. per gallon formulations (Dynasty) for seed treatment at 0.10-3.75 fl. oz. per 100 lbs. of seed. REI: 4-hour. FRAC 11. White Mold (Timber Rot, Drop, Stem Rot) of Multiple Crops - Sclerotinia Fungus This soil pathogen is long-lived in the soil, and has a wide host range on broadleaved crops and weeds, including beans, vine crops, lettuce, tomatoes, peppers, and cole crops. It goes by other names in other crops, such as Drop, White Mold, Stem Rot, and Timber Rot. It is more commonly where humidity and temperatures are high. The fungus often infects flowers, which then drop off and infect the stems that they land on. But, the pathogen can also infect stem tissue around the root crown. The stems take on a woody appearance and can split open, revealing small black pellets that are the overwintering body of the pathogen. Non-Pesticide Avoid fields with a history of the problem. Rotate to a non- broadleaf crop, such as grass grains or sweet corn for >6 years. Avoid excess nitrogen. Reduce overhead irrigation if disease is present. Prompt destruction of the finished crop with tillage to rapidly breakdown tissue is an important method to prevent disease build-up. Pesticide Contans WG (5) (Coniothyrium minitans strain CON/M/91-08) | 1-6 lbs. per acre. Apply immediately after

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