Vegetable Briefs

• Cucurbit downy mildew was reported on cucumber in Caroline County, MD this Friday (6/21). This is the first report of CDM this year in the region. All cucurbit growers should scout their fields on a regular basis and consider adding downy mildew specific fungicides to their regular maintenance program.
• Pith necrosis has been reported on tomato.
• Basil downy mildew was reported near Vineland last week! All basil growers should continue to scout their fields and apply preventative fungicides.
• Late blight was reported on tomato on the Eastern Shore of Virginia and in Montgomery County, MD this past week. These are the first reports of Late blight in the region this year.
• To track late blight in the US please visit http://usablight.org/
• Want more information on what’s going on, please sign up for the Jersey Vegetable Crop Ag Updates at: http://jerseyvegcropsagupdates.blogspot.com/.

Vegetable Disease Update – 6/23/13

Basil

Downy mildew – has been reported for the first time this season near Vineland, NJ. Basil infections can originate from infested seed or from southern weather patterns. No cucurbit downy mildew has been reported in our region to date (in recent years based on observations, both pathogens tend to appear around the same time) so source of infection may be most likely through seed. All basil growers should scout their fields on a regular basis. All sweet basils are susceptible to the disease. Lemon/Lime and Spice-type basils appear to be tolerant/resistant. Control of basil downy mildew begins with planting resistant-types (when possible) and preventative fungicide applications BEFORE basil downy mildew appears on your farm. Weekly applications of a phosphite fungicide (FRAC code 33) such as K-Phite, Pro-Phyt, Rampart or other labeled phosphite at a high rate will help suppress basil downy mildew development. Ranman (cyazofamid, 21) at 2.75 to 3.0 fl. oz 400SC/A now has a federal label and will also help to suppress basil downy mildew development. Our research has shown that if fungicide applications are started AFTER the pathogen has been found in the field will result in very poor season-long control. For organic basil producers, unfortunately, all organic fungicides we have evaluated over the past three years have failed to provide any meaningful control of basil downy mildew.  For more information, please see “Controlling basil downy mildew” from May 13, 2013.

Cucurbit downy mildew – Please see article from 06/07/13 for recurrent recommendations.

Pepper

Bacterial leaf spot – Symptoms of bacterial leaf spot on pepper leaves include small, brown water-soaked lesions that turn brown and necrotic in the centers. Spots may coalesce and form large blighted areas on leaves and premature defoliation can occur. On fruit, brown lesions can form which have a roughened, cracked wart-like appearance. High temperatures, high relative humidity and rainfall favor Bacterial spot development. Loss from Bacterial spot can be reduced somewhat by maintaining high levels of fertility, which will stimulate new growth. Applying a fixed copper (M1) at labeled rates or may help suppress spread. Quintec (quinoxyfen, 13) at 6.0 fl. oz/A is now labeled for the suppression of bacterial leaf spot in pepper in the mid-Atlantic region. Please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide for more information.

Phytophthora blight – Plant loss can be severe in all pepper types. Phytophthora blight typically develops in low-lying areas of fields after a heavy rain and can spread quickly throughout the entire field. Planting on a ridge or raised, dome-shaped bed will help provide better soil drainage. Use a minimum 3-year crop rotation with crops other than peppers, cucurbits, lima and snap beans, eggplants, or tomatoes. In fields with low-lying or wet areas, plant only Phytophthora-tolerant cultivars such as ‘Paladin’, ‘Aristotle’, ‘1819’, or ‘Revolution’. In heavily-infested fields with a known history of Phytophthora blight, plant only tolerant cultivars to help reduce plant losses. If mefenoxam-insensitivity is known to exist in a field/farm, plant only tolerant cultivars. Do not apply mefenoxam or metalaxyl in fields where insensitivity is known to exist.

For control of the crown rot phase of Phytophthora blight, apply:

mefenoxam–1.0 pt Ridomil Gold 4SL/A or 1.0 qt Ultra Flourish 2E/A or metalaxyl (MetaStar)–4.0-8.0 pt 2E/A at transplanting and 30 days later or,
Presidio (fluopicolide, 43) at 3.0-4.0 fl. oz 4SC/A when conditions favor disease development, or
Ranman (cyazofamid, 21) at 2.75 fl oz 400SC (Ranman may be added to transplant water, see label for restrictions).
Phosphite materials (FRAC code 33) such as Rampart, ProPhyt, K-Khite may also be applied with one of the above to help suppress Phytophthora blight.