potato 5-9-12 CLEAN - Vegetableipmasia.org

ORGANIC POTATO PRODUCTION yellow to mahogany. Eggs are small, pearly white, and spherical. The newly hatched larva or wireworm is white and 2/25 inchlong. Mature larvae are cylindrical, tan, and range from 1/2 to 1 inch in length. Wireworms can create holes in potato tubers.See Cornell HUlife cycleUH and HUdamageUH (Reference 117).Relative risk: Wireworm can be serious especially if potatoes are grown in fields directly after sod, grassy weeds, or hay.Management Option Scouting/thresholds Site selection Crop rotation Cover crops Resistant varieties Cultivation Sanitation Notes Recommendation for Wireworms Prior to planting, bait stations can be used to monitor populations. Delay sampling as late in the spring as possible because wireworms burrow deep into the soil in the winter and move up only after the soil warms. Place several ounces of coarse whole-­‐wheat flour or a mixture of untreated corn and wheat seed or pieces of carrot or potato into a fine mesh pouch (e.g. panty hose), and bury six to 14 inches. Cover the soil over the bait station first with a piece of black polyethylene plastic and then with a piece of clear polyethylene film. Secure the edges of the film with soil. Prior to planting, remove the soil above and around the bait station and count the larvae in and around the bait. Alternatively, sample in midsummer by sifting one square foot of soil to a depth of six to 14 inches and counting the wireworms. Use a box with a base made of 1/4-­‐mesh hardware cloth as a sieve. Take six to 12 samples, starting in low, wet areas. Threshold: if half or more of the bait stations or soil samples contain one or more wireworms, don’t plant potatoes on that ground. Avoid planting in poorly drained soils or wet areas. Allow 3 years between grassy crops or cover crops to avoid wireworm with the exception of grains or grasses that are only in the field for part of the season. Millipedes are sometimes found in association with wireworms and produce similar damage to tubers. Rotations of red or sweet clover of more than one year may promote millipede populations. Full season cover crops can allow wireworm populations to build. Use shorter season or fall seeded cover crops and cultivate into soil in the spring to avoid buildup. No resistant varieties are available. Cultivation is effective at reducing wireworm populations. Infestation can be minimized by keeping land free of grassy weeds during the egg-­‐laying period (May through late June). Avoid having actively decomposing organic matter during the growing season. No insecticides are available for control of wireworms but cultural practices can be partially effective. 15.9 Symphylan, Scutigerella immaculataTime for concern: May through JulyKey characteristics: Garden symphylans, sometimes called garden centipedes, are soil inhabiting arthropods of the ClassSymphyla, with 14 body segments and 12 pairs of legs. The quick moving adults are less than ½ inch long, white and slenderwith prominent antennae. Immature stages only have six pairs of legs. They feed on decaying organic matter and root hairs,stems and tubers. See National Sustainable Agriculture Information Service HUpublicationUH (Reference 118) for photos and moreinformation.Relative risk: This pest is rare and only occurs sporadically in certain fields and in localized areas within a field.772012