Alliums: 

Embellesia skin blotch of garlic has been a common sight this season. Common symptoms are dark discoloration of wrapper leaves and, occasionally, the center scape. The disease is widespread and affected bulbs can be saved for seed and sold so long as the lesions are superficial. Garlic cloves can be surface sanitized by submerging cloves (typically in a mesh onion bag) in a 1:256 (25 fl. oz. per 50 gallons of water) dilution of OxiDate 5.0 for 2 minutes then allowing cloves to dry.

Allium leafminer activity is expected to begin next week (early September). Organic growers should cover fall leeks and scallions now if possible. More information on management options can be found here.

Brassicas:

Fall caterpillar pests can be a serious challenge in brassica crops as the period of activity for imported cabbageworm, diamondback moth, and cross-striped cabbageworm can extend for over two months. Bacillus thuringiensis (Bt) products including Agree, XenTari, Deliver, and Javelin are most effective on small caterpillars; typically two sequential applications 7-10 days apart at the beginning of caterpillar activity is the best use of these insecticides. Conventional growers can then rotate to Radiant (spinosyn) for up to two sequential applications followed by up to two sequential applications of Proclaim (emamectin benzoate). Organic growers have fewer options, especially since most diamondback moth populations in NY are resistant to pyrethroids (PyGanic, Warrior, Lamcap, OLF). Organic growers can begin with two Bt applications followed by two sequential applications of Entrust (spinosad) if row covers or exclusion netting are not practical.

Brassica downy mildew has been found in a broccoli planting in the Hudson Valley. Lesions begin as small yellow leaf spots that later turn brown with blue or black lace-like markings. Under humid conditions, especially in the morning, look for white downy mold on leaf undersides. Dr. Chris Smart at Cornell University has conducted fungicide efficacy trials for downy mildew control on brassicas. Manzate Pro-Stick (mancozeb, FRAC M3, only labeled for broccoli and cabbage) is effective when used preventively and can be alternated with Champ Formula 2F (copper hydroxide, FRAC M1). Bravo Weather Stik (chlorothanlonil, FRAC M5) and Presidio (fluopicolide, FRAC 43, Presidio must be tank mixed with another fungicide with a different mode of action for resistance development prevention) are the other two fungicides recommended by Dr. Smart. For organic growers, avoidance is crucial. Increase plant spacing to improve air circulation and minimize leaf-to-leaf disease transmission. Make sure to rotate fields out of brassicas for at least three years and work to control cruciferous weeds that may also act as sources for inoculation. Most OMRI-approved fungicides have little demonstrated efficacy. Organic copper formulations, such as Badge X2 (copper oxychloride + copper hydroxide, FRAC M1) are the best bet, but products like Double Nickel 55 (Bacillus amyloliquefaciens strain D747, FRAC 44), Stargus (Bacillus amyloliquefaciens strain F727 cells and spent fermentation media, FRAC 44) and Regalia (Reynoutria sachalinensis extract, FRAC P5) are also labeled for downy mildew on most cole crops and have shown some reduction in disease severity in trials when used preventatively.

 Chenopods (Beets, Chard, Spinach):

Nothing new to report this week.

Cucurbits: 

Late last week we had several confirmed reports of cucurbit downy mildew (CDM) infecting winter squash and pumpkins from New Jersey. Cucumbers continue to be the main target of CDM, but this is a warning that ALL cucurbits should be protected with fungicides. The concern with CDM in winter squash and pumpkins is similar to that with powdery mildew – these diseases will deteriorate leaf tissues. When that happens, fruit are more exposed to direct sunlight, which increases the chances of sunscald. Fruit may also not reach maturity normally and therefore not produce the sugars that are necessary for flavor and storage. Cucurbit downy mildew fungicides can be found by clicking on this link.

Lettuce:

Watch for thrips migration into adjacent leafy greens plantings after onion crops reach maturity. There are a number of effective insecticide options for managing thrips in lettuce, including Radiant (spinosyn) with a 1 day PHI for most greens, Exirel (cyantraniliprole) with a 1 day PHI, and Minectro Pro (abamectin + cyantraniliprole) with a 7 day PHI. Thrips feeding injury shows up as pock-marked bronzing especially on older leaves.

Nightshades: 

Tomato quality seems to be holding up well in parts of the ENY region that have received less rain. Early blight continues to be the major pest we are seeing, although other diseases are also more widespread (bacterial, leaf mold, septoria, and others) in the north where rainy conditions persist. We have not yet found late blight in ENY, and the disease continues to be confirmed only in the western/central part of the state. Radial and concentric cracking in field tomatoes are widespread in the north due to excessive rain.

Stink bugs and their damage are also easily found, especially in small fruited varieties like grapes and cherry tomatoes. Good spray coverage is necessary to control stink bugs because they are secretive and like to hide deep in the canopy. Actara (thiamethoxam), Baythroid XL (beta-cyfluthrin) and Leverage 360 (imidacloprid + beta-cyfluthrin) are all labeled on tomatoes with a 0 days to harvest interval (12 hour re-entry interval).

Peppers and eggplant are also looking quite well with very good to excellent size in most parts of the region. Verticillium wilt is prevalent in eggplant plantings and the only thing to do is to make sure you maintain uniform watering to relieve some of the stress from the disease.

Northern corn leaf blight (NCLB) can be found in quite a few sweet corn plantings and will continue to move in with the heavy dews and frequent rains. If allowed to spread it can deteriorate leaf cover and move onto the ears and flag leaves of the ears. For corn that will be picked within a couple days, your fungicide choices are limited due to some fungicides with a long preharvest interval (PHI). Delaro and Protegam YLD (both containing trifloxystrobin + prothiocomazole, Group 11 & 3) have a 0 day PHI. For younger corn there are lots of fungicide choices with 7-21 days preharvest intervals. Be aware that most of the fungicides labeled for NCLB are premixes of several different classes or groups of fungicides so be sure to pay attention and rotate.