potato 5-9-12 CLEAN - Vegetableipmasia.org

ORGANIC POTATO PRODUCTION Table 12.10 Pesticides Labeled for Management of White Mold Class of Compounds Product Name (active ingredient) (Bacillus subtilis) Sonata (Bacillus pumilis) OTHER PERpose Plus (hydrogen peroxide/dioxide) Trilogy (hydrophobic extract of neem oil) Product Rate PHI (days) 2-­‐4 qts/A 0 4 ? 1 fl oz/Gal (initial/curative) 0.25-­‐0.33 fl oz/gal (weekly/preventative) 0.5-­‐1% in 25-­‐100 gal of water/A -­‐ REI (hours) Efficacy Comments 1 (interior); until dry (field) ? For initial or curative use, apply higher rate for 1 to 3 consecutive days. Then follow with weekly/preventative treatment. For weekly or preventative treatments, apply lower rate every five to seven days. At first signs of disease, use curative rate then resume weekly preventative treatment. -­‐ 4 ? Limited to a maximum of 2 lbs/acre/application. 55B 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 12.11 Potato Common Scab, Streptomyces scabies and S. acidiscabiesTime for concern: Flower to end of season. Thought to be more prevalent during dry weather.Key characteristics: Both species of Streptomyces cause similar symptoms that range from superficial russeting to deeppitting. Bacteria survive in the soil, in cull potatoes left in the field and on infected seed pieces in storage. Disease does notprogress in storage but the pathogen infects newly planted tubers through the lenticels or through wounds. The severity ofcommon scab is significantly reduced when soil pH is maintained below 5.2. See Cornell HUfact sheetUH (Reference 72).Relative risk: Most common on soils with pH 5.5-7.5; usually does not reduce yields but cosmetic damage can significantlyaffect marketability, especially in tablestock potatoes.Management Option Scouting/thresholds Site selection Cover crops Crop rotation Resistant varieties Seed selection Irrigation Organic matter Recommendation for Common Scab No thresholds are available. Look for and keep a record of disease incidence in late August and at harvest. Fields with a history of scab should be avoided. Light-­‐textured soils favor scab infection. Maintaining pH levels below 5.2 will prevent common scab, although this practice can make nutrient management and crop rotations difficult and may limit crop diversity. Although severe scab occurs at high soil pH, Streptomyces acidiscabies can occur in soils with a pH below 5.2. There is no evidence that planting and plowing under a legume cover crop prior to planting potatoes increases the incidence of potato scab. Biofumigant cover crops, such as brassicas, may suppress scab. Rotate with alfalfa, rye, soybeans and corn. Rotate with green manure crops such as rye, millet and oats. Do not rotate with common scab hosts such as spinach, turnip, parsnip, radish, beet, and carrot. Planting resistant or tolerant varieties in fields where scab has been a problem is useful, but not sufficient to prevent scab under high disease pressure. Superior is the standard for resistance in the Northeast. Other very resistant, tolerant, resistant or moderately resistant varieties include Andover, Atlantic, Carola, Chieftain, Eva, Genesee, Keuka Gold, Lehigh, Reba, Red Norland, Salem, Yukon Gold. Avoid planting scab-­‐infested seed. Maintain moisture during the six weeks following tuberization. Warnings against the use of manure and legume green manures that appear in guidelines for 442012