Damping-off – To help control losses due to damping-off pathogens apply Ridomil Gold (mefenoxam, FRAC code 4) at 1 to 2 pt/A, MetaStar (metalaxyl, 4) see label, or azoxystrobin at 0.40 to 0.80 fl oz 2.08SC/1000 row ft (for Rhizoctonia only), or Ridomil Gold at 1.0 to 2.0 pt/A 4SL plus azoxystrobin at 0.40 to 0.80 fl oz 2.08SC/1000 row ft. in a band up to 7 in. after seeding. To help control damping-off pathogens in Collards and Kale only: Apply Uniform (mefenoxam + azoxystrobin, 4 + 11) at 0.34 fl oz 3.66SE/1000 ft row. For more information please see 2016 New Jersey Commercial Vegetable Production Recommendations Guide.
Downy Mildew and Alternaria – Symptoms of downy mildew include purple to yellowish-brown spots on upper leaf surfaces. A grayish-white spore mass will develop and cover the underside of leaves under ideal temperatures (night temperatures of 46 to 61°F and day temperatures below 75°F. Downy mildew can kill young plants. Heavily infected leaves may drop providing entry points for bacterial infections (black rot and soft rot). Symptoms of Alternaria on infected leaves include small, expanding circular lesions with concentric rings that may have a ‘shot-hole’ appearance as lesions age. Heavily infected seedlings may result in damping-off. Control of Downy mildew and Alternaria begin with preventative fungicide applications. Please see Table on pages F34-F35 of the 2016 NJ Commercial Vegetable Production Recommendations to determine which fungicides are labeled for each specific crop and disease.
Bottom Rot/Drop – Spring season is beginning and growers should take precautions to help control Bottom rot (Rhizoctonia) and Lettuce drop (Sclerotinia) which may cause potential problems. For Bottom rot, apply Endura 70W (boscalid, FRAC code 7) at 8.0 to 11.0 oz 70W/A (only 2 applications per season), or iprodione (FRAC code 2) at 1.5 to 2.0 lb 50WP/A or OLF should be applied one week after transplanting or thinning and 10 and 20 days later (only 3 applications per season). For Lettuce drop, apply Endura (FRAC code 7) at 8.0 to 11.0 oz 70WG/A, or iprodione (FRAC code 2) at 1.5 to 2.0 lb/A, or Quadris (azoxystrobin, 11) at 0.40 – 0.80 fl. oz/1000 row ft 2.08SC, or Cannonball (fludioxonil, 12) at 7.0 oz 50WP/A beginning one week after transplanting or thinning and again at 10 and 20 days later. Uniform (mefenoxam + azoxystrobin, 4 +11) applied at transplanting or seeding will help control damping-off pathogens as well as provide early-season downy mildew control. For more information on control of Bottom rot and Lettuce drop and other important diseases of lettuce please see the 2016 New Jersey Commercial Vegetable Production Recommendations Guide.
Bacterial leaf blight – Symptoms include numerous black, irregular ‘greasy’ lesions on leaves and can be problematic during excess rainfall or when overhead irrigation has been used extensively. The bacterium can survive on weeds and infected debris left in the field. Abandoned plantings should be thoroughly worked back into the soil to allow decomposition of infected plants. Copper fungicide applied on a regular basis may help to suppress the spread of the disease.
Bacterial spot and speck – Tomato transplants with suspected symptoms can be treated with streptomycin (Agri-Mycin 17, Agri-Strep, 25) at 1 lb/100 gallons, or 1.25 teaspoon per gallon every 4 to 5 days prior to transplanting. Additionally, Kocide 3000 (copper hydroxide, FRAC code M1) has a greenhouse label for speck and spot control in the greenhouse. Apply ½ to 1.5 TBSP per 1000 sq ft. every 5 to 10 days. Remember, phytotoxicity is an important issue when apply copper in enclosed structures, see label for cautions, restrictions and liabilities. After transplanting, apply Actigard at 0.33 oz 50WG/A (see label for use), or fixed copper (M1) at 1 lb a.i./A plus a mancozeb (Dithane, Manzate, M3) at 1.5 lb 75DF or OLF, or ManKocide (M1 + M3) at 2.5 to 5.0 lb 61WP/A on a 7 day schedule. For organic options, please see Table E14 on pages E52-E54 in the 2016 New Jersey Commercial Vegetable Production Recommendations Guide.