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Carrots
Leaf blights – Powdery mildew, Alternaria and Cercospora. Alternaria and Cercospora are two soil-borne fungal pathogens that may cause early defoliation in carrots reducing yields and making harvest difficult. Both pathogens produce distinct symptoms on carrots. Powdery mildew causes characteristic white, powdery lesions on foliage. Symptoms of Alternaria include irregular, dark brown to black spots which typically show up on older leaves first. Cercospora leaf spots are round, grayish-brown and are more prevalent on younger foliage. Both leaf blights typically start at the margins of leaflets and as more spots develop leaflets begin to wither and die. Symptoms similar to leaf infections can develop on stems and petioles.
Control of both diseases begins with regular scouting and preventative fungicide applications on susceptible varieties. Apply Quadris (azoxystrobin, 11) at 9.0 to 15.5 fl. oz 2.08F/A, or Cabrio 20EG (pyraclostrobin, 11) at 8.0 to 12.0 oz/A, or Pristine (pyraclostrobin + boscalid, 11 +7) at 8.0 to 10.5 oz 38WG/A tank-mixed or alternated with chlorothalonil (M5) at 1.5 to 2 pt/A. For Alternaria only: Apply a tank mix of 1.5 to 2.0 pt/A chlorothalonil plus Endura (boscalid, 70 at 4.5 oz 70W/A, or Switch (cyprodinil + fludioxonil, 9 +12) at 11.0 to 14.0 oz 62.5WG/A, or iprodione at 1.0 to 2.0 pt 50WP/A. For more information on tolerant varieties and control please the 2013 New Jersey Commercial Vegetable Production Recommendations.
Cole Crops
Damping off and Rhizoctonia – To help control losses due to damping-off pathogens apply Ridomil Gold (mefenoxam, FRAC code 4) at 1.0 to 2.0 pt/A 4SL or Quadris (azoxystrobin, 11) at 0.40 to 0.80 fl oz 2.08SC/1000 row ft (for Rhizoctonia only), or Ridomil Gold at 1 to 2 pt/A 4SL plus Quadris at 0.40 to 0.80 fl oz 2.08SC/1000 row ft. in a band up to 7 in. after seeding. For more information please see 2013 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 (i.e., 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. Use one of the following at the first sign of disease and continue every 7 to 10 days (Please refer to the pesticide table on page F24 of the 2013 NJ Commercial Vegetable Production Recommendations to determine which fungicide is labeled for each specific crop.): Quadris (azoxystrobin, 11) at 6.0 to 15.5 fl oz 2.08SC/A, or chlorothalonil (M5) at 1.5 pt 6F/A or OLF, or Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 oz 20EG/A, or Endura (boscalid, 7) at 6.0 to 9.0 oz 70WG/A, or Ridomil Gold Bravo (mefenoxam + chlorothalonil, 4 + M5) at 1.5 lb 76.5 WP/A, or Switch (cyprodinil fludioxonil , 9 +12) at 11.0 to 14.0 oz 62.5WG/A (Alternaria only), or Fontelis (penthiopyrad, 7) at 14.0 to 30.0 fl oz 1.67SC/A (Alternaria only). For downy mildew only, apply Actigard (acibenzolar-S-methyl, P) at 1.0 oz 50WG/A (begin applications 7-10 days after thinning and re-apply every 7 days for a total of 4 applications per season), or Aliette (fosletyl Al, 33) at 3.0 to 5.0 lb 80WDG/A (on 14-day schedule).
Cucurbits
Black rot – Black rot is the fruit rot phase of Gummy stem blight. Symptoms usually appear (i.e., as a descriptive dry rot of the rind) on fruit as it is left in the field to mature or later in storage (see VDOW). Tank mix and alternate chlorothalonil at 2.0 to 3.0 pt/A with Pristine (boscalid + pyraclostrobin, 7 + 11) at 12.5 to 18.5 oz WG/A, or Switch (cyprodinil + fludioxonil, 9 + 12) at 11.0 to 14.0 oz 62.5WG/A, or Folicur (tebuconazole, 3) at 8.0 fl oz 3.6F/A, or Inspire Super (difenoconazole + cyprodinil) at 16.0 to 20.0 fl oz 2.8F/A.
Leeks
Purple blotch – Symptoms of Purple blotch include tannish-brown, elongated, concentric, circular lesions with chlorotic margins with lesions running parallel with leaf veins. Control of Purple blotch begins with preventative fungicide applications. Please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide for more information.
Lettuce
Bottom Rot/Drop – For Bottom Rot, Endura 70WG (boscalid, 7) at 8.0 to 11.0 oz/A, or iprodione (FRAC code 2) at 1.5 to 2.0 lb/A should be applied one week after transplanting or thinning and 10 and 20 days later. For Drop, the biological Contans 5.3WG at 2.0 to 4.0 lbs/A pre-plant can be incorporated at a depth of 1 to 2 inches. Apply Cannonball (fludioxonil, 12) at 7.0 oz 50WP/A, or iprodione (FRAC code 2) at 1.5 to 2.0 lb/A, or Endura (boscalid, 7) at 8.0 to 11.0 oz 70W/A, or Quadris (azoxystrobin, 11) at 0.40 to 0.80 fl oz. 2.08SC/A beginning one week after transplanting or thinning and again at 10 and 20 days later. For more information on control of Bottom Rot and Drop and other important diseases of lettuce please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
Parsley
Septoria Blight /Bacterial (blight) leaf spot – Leaf spots caused by Septoria blight are easily distinguished by small, angular to round leaf spots with grayish-brown centers with a definitive dark, brown margin. Numerous black fruiting bodies develop in the center of lesions. Septoria blight is spread by wind-driven rain, heavy dews and overhead irrigation. Workers and equipment may also spread the disease during wet conditions.
Best management practices include i) proper crop rotations of at least 2 years and by using clean or treated seed ii) scouting fields early for symptom development iii) keeping workers and equipment out of fields with wet foliage iv) plowing under residue of harvested crop and avoid planting in fields adjacent or near previously infected fields. Rotate applications of Quadris (azoxystrobin, 11) at 6.0 to 15.5 fl oz 2.08SC/A or Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 oz 20WG/A with Tilt (propiconazole, 3) at 3.0 to 4.0 fl oz. 3.6F/A every 7 days. A fixed copper at labeled rates can also be included if bacterial leaf spot is an issue.
Peppers
Anthracnose fruit rot- Growers with peppers in fields with a history of pepper anthracnose should scout on a daily basis and apply fungicides preventatively. Pepper anthracnose can be very difficult to control once established. Strip picking and removing all fruit from ‘hot spots’ when they first appear may help suppress spread of the pathogen. Preventative fungicide applications should begin shortly before or at flowering. Use a heavy volume of water and make sure coverage is extremely good. Apply high rates of chlorothalonil or Manzate weekly and/or rotate weekly with Quadris (azoxystrobin, 11) or Cabrio (pyracolostrobin, 11). Please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide for more information.
Tomato
Early blight, Septoria leaf spot and anthracnose fruit rot – Early blight is being reported on tomato. Weekly maintenance fungicide programs which target early blight will also help control septoria leaf spot and Anthracnose fruit rot. Control of anthracnose fruit rot begins while green fruit are maturing. Remember, anthracnose infections take place on green fruit and symptoms show up later in the season on red, mature fruit. To successfully control anthracnose, protectant fungicides need to be applied on a regular basis as fruit are forming. Organic growers should apply OMRI-approved copper-based or other labeled products on a weekly basis to help suppress the development of early blight, septoria leaf spot and anthracnose fruit rot.
Sunflower
Septoria leaf spot- Septoria leaf spot was identified on sunflower this past week (see VDOW). The pathogen overwinters in debris in the soil and infects lower leaves first, working its way up the stem. Humid, wet weather favors the development and spread of the disease. Controlling SLS on sunflower begins with good crop rotation and preventative fungicide applications. Apply Headline (pyraclostrobin, 11) at 6.0 to 12.0 fl oz/A (21 day PHI; 12 hr REI).
Pumpkin
Sunscald injury – Sunscald injury occurs when pumpkin fruit are suddenly exposed to heavy sunlight during the latter stages of fruit ripening during the fall. Sunscald injury often occurs when pumpkin plants become prematurely defoliated in the early fall by powdery mildew or downy mildew or when vines collapse due to Phytophthora blight or bacterial wilt. Symptoms of sunscald injury include the collapsing of rind tissue on the side of the fruit which is in direct contact with the afternoon sun. Sunscald injury often develops as a pinkish-red color on exposed fruit which becomes flat in appearance. Over time fruit tissue may become tan to brown and secondary pathogens often invade the sunscald injured areas of the fruit. To help reduce the potential for sunscald injury, maintain foliage for as long as necessary, especially if fruit are going to be left in the field for long periods.
White mold or Sclerotinia rot – White mold may cause problems when pumpkins are planted in the same field each year and in fields where other susceptible crops such as bean have been grown. Development of white mold is favored by prolonged, cold wet weather. Symptoms often begin to show up as a soft, mushy area around the stem as the fruit reaches maturity. Infected fruit often collapse inward near the stem. Large, black fruiting bodies (sclerotia) may be produced around infected areas. Sclerotia serve as overwintering and long-term survival structures. A long crop rotation is necessary to help control white mold. Infected fruit should be removed from the field immediately. Early maturing fruit left in the field for a prolong time period are susceptible to white mold.
Spinach
Downy Mildew – Beginning 2 to 3 weeks after emergence (and prior to symptom development), apply the following on a 7 to 10 day schedule: Quadris (azoxystrobin, 11) at 6.0 to 15.5 fl oz 2.08SC/A, or Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 oz 20EG/A, or Reason (fenimadone, 11) at 5.5 to 8.2 fl oz 500SC/A, or Tanos (famoxodone + cymoxanil, 11 + 27 ) at 8.0 to 10.0 oz 50W/A. Rotate to one of the following fungicides: Ranman (cyazofamid, 21) at 2.75 fl oz 400F/A, Revus (mandipropamid, 40) at 8.0 fl oz 2.08F, or Presidio (fluopicolide, 43) at 3.0 to 4.0 fl oz 4SC/A, or Actigard (acibenzolar-S-methyl, P) at 0.50 to 0.75 oz 50WG/A, or Aliette (fosetyl Al, 33) at 3.0 lb 80WDG/A, or fixed copper (FRAC code M1) at labeled rates (Copper containing fungicides may cause some phytotoxicity), or Ridomil Gold Copper (mefenoxam + copper, 4 + M1) at 2.5 lb 65WP/A (on 14-day schedule). For more information please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
[White Rust and Downy Mildew] – Prior to symptom development, apply the following on a 7 to 10 day schedule: Quadris (azoxystrobin, 11) at 12.0 to 15.5 fl oz 2.08SC/A, or Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 oz 20EG/A, or Reason (fenimadone, 11) at 5.5 to 8.2 fl oz 500SC/A, or Tanos (famoxodone + cymoxanil, 11 + 27 ) at 8.0 to 10.0 oz 50W/A. Rotate to one of the following fungicides: Ranman (cyazofamid, 21) at 2.75 fl oz 400F/A, Revus (mandipropamid, 40) at 8.0 fl oz 2.08F, or Presidio (fluopicolide, 43) at 4.0 fl oz 4SC/A, or Actigard (acibenzolar-S-methyl, P) at 0.50 to 0.75 oz 50WG/A, or Aliette (fosetyl Al, 33) at 3.0 lb 80WDG/A, or fixed copper (FRAC code M1) at labeled rates (Copper containing fungicides may cause some phytotoxicity), or Ridomil Gold Copper (mefenoxam + copper, 4 + M1) at 2.5 lb 65WP/A (on 14-day schedule). For more information please see the 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
