- Asparagus: Phytophthora crown and spear rot
- Cabbage: Damping-off
- Cole crops: Downy Mildew and Alternaria
- Leeks (overwintered, spring transplanted): Purple blotch
- Lettuce: Bottom Rot/Drop
- Parsley: Septoria Blight/Bacterial (blight) leaf spot
- Strawberry: Anthracnose fruit rot; Botrytis (Gray Mold) and Blossom blight
Phytophthora crown and spear rot – In fields with low spots (poorly drained soils) or fields with a history of crown and/or spear rot apply Ridomil Gold 4SL (mefenoxam, 4) at 1.0 pt/A, or Ultra Flourish 2E/A (mefenoxam, 4) at 2.0 pt/A, or MetaStar 2E (metalaxyl, 4) at 2.0 qt/A over beds just before 1st harvest. For new plantings, apply the same after planting or after crown covering. Do not apply Ridomil or MetaStar one day prior to harvest or illegal residues may result. For more information please see 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
Damping-off – To help control losses due to damping-off pathogens apply Ridomil Gold (mefenoxam, FRAC code 4) at 1 to 2 pt/A 4SL, MetaStar (metalaxyl, 4) see label, or Quadris (azoxystrobin, 11) at 0.40 to 0.80 fl oz 2.08SC/1000 row ft (for Rhizoctonia only), or Ridomil Gold at 1.0 to 2.0 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. 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 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 (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 F27 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 76.5WP/A (14-day schedule), or Switch (cyprodinil, 9) at 11.0 to 14.0 oz 62.5WG/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). For more information please see 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
Leeks (overwintered, spring transplanted)
Purple blotch – Purple blotch may survive on infected plant material in overwinter plantings and may cause problems in spring transplanted fields and seedbeds. As the weather begins to warm up and spring showers arrive Purple blotch may become problematic in some fields. 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.
Alternate and/or tank mix chlorothalonil (M5) at 1.5 to 3.0 pt 6F/A the following fungicides on a 7 to 10 day interval:
Quadris (azoxystrobin, FRAC code 11) at 6.0-12.0 fl oz 2.08SC/A, or
Endura (boscalid, 7) at 6.8 oz 70WP/A, or
Pristine (pyraclostrobin + boscalid, 11 + 7) at 10.5 to 18.5 oz 38WP/A, or
Folicur (tebuconazole, 3) at 4.0 to 5.0 fl oz 3.6F/A, or
Inspire Super (difenconazole + cyprodinil, 3 + 9) at 16.0 to 20.0 fl oz. 2.82SC/A.
Applications of Quadris or Pristine at high rates will also help suppress Downy mildew.
Bottom Rot/Drop – Spring lettuce 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 2013 New Jersey Commercial Vegetable Production Recommendations Guide.
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:
- proper crop rotations of at least 2 years and by using clean or treated seed
- scouting fields early for symptom development
- keeping workers and equipment out of fields with wet foliage
- 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 – 16.0 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. Bacterial leaf spot (Pseudomonas syringae) of parsley can also show up at the same time as Septoria blight. Leaf spots caused by Bacterial blight appear as small brown to black spots on the leaves. The pathogen can be soil or seed borne and develops during cool, moist weather. The disease spreads during cool, rainy weather or with overhead irrigation; and is exacerbated by high plant density. The same control measures listed for Septoria will assist in preventing the spread of Bacterial leaf spot as long as the fixed copper is included with azoxystrobin and the fungicides are applied preventatively. If Oxidate is used, follow the label carefully.
Anthracnose fruit rot – Strawberry anthracnose can be extremely destructive during warm, wet weather causing significant fruit rot. Symptoms of Anthracnose include blackish-brown circular spots on maturing green fruit and soft, sunken (flat) circular lesions on ripe fruit. On ripe fruit, lesions can expand rapidly and are often covered with a pinkish-orange spore mass. Spores are spread from infected to healthy fruit with splashing water. Control of Anthracnose always begins with a 7 to 10 day preventative spray program no later than 10% bloom and/or prior to disease development.
For control apply the following combinations:
- Pristine (pyraclostrobin + boscalid, 11 + 7) at 18.5 to 23.0 oz 38WG/A
- Captan (M3) at 4.0 lb 50WP/A, or Switch ( cyprodinil + fludioxonil,9 +12) at 11.0 to 14.0 oz 62.5 WG/A, or Captevate (captan + fenhexamid, M3 + 17) at 3.5 to 5.25 lb 68WDG/A
- Pristine (pyraclostrobin + boscalid, 11 + 7) at 18.5 to 23.0 oz 38WG/A
For subsequent applications, rotate and tank mix between two or more of the following fungicides:
Captan (M3) at 4.0 lb 50WP/A, or Abound (azoxystrobin, 11) at 6.0 to 15.5 fl oz 2.08SC/A, or
Cabrio (pyraclostrobin, 11) at 12.0 to 14.0 oz 20EG/A, or Captevate (captan + fenhexamid, M3 + 17) at 3.5 to 5.25 lb 68WDG/A, or Pristine (pyraclostrobin + boscalid, 11 + 7) at 18.5 to 23.0 oz 38WG/A, or Switch ( cyprodinil + fludioxonil,9 +12) at 11.0 to 14.0 oz 62.5 WG/A
To help manage fungicide resistance development, do not make more than 2 consecutive applications of either: Pristine (pyraclostrobin + boscalid, 11 + 7), Cabrio (pyraclostrobin, 11) or Abound (azoxystrobin, 11) before switching to another fungicide chemistry.
Botrytis (Gray Mold) and Blossom blight – can cause serious losses in strawberry plantings in high tunnels and the field if not controlled properly. Development is favored by moderate temperatures (59 to 77 °F) with prolonged periods of high relative humidity and surface wetness. Control of Gray mold begins with preventative fungicide applications. Apply at 5 to 10 percent bloom and every 10 days until harvest. During periods of excessive moisture, spray intervals of 5 to 7 days may be necessary. Rotate fungicide chemistries to aid fungicide resistance management.
- Application #1: Captan (M3) at 4.0 lb 50WP/A plus Topsin-M at 1.0 lb 70WP/A , or Switch (cyprodinil, 9) at 11.0 to 14.0 oz 62.5WG/A
- Application #2 : Pristine (pyraclostrobin + boscalid, 11 + 7) at 18.5 to 23.0 oz. 38WG/A, or Elevate (fenhexamide, 17) at 1.1 to 1.5 lb 50WDG/A
- Application #3: same options as application #1.
For subsequent applications, rotate between two or more of the following fungicides:
Captan (M3) at 4.0 lb 50WP/A, or Switch (cyprodinil + fludioxonil, 9 + 12) at 11.0 to 14.0 oz. 62.5WG/A, or Pristine (pyraclostrobin + boscalid, 11 +7) at 18.5 to 23.0 oz 38 WG/A, or Switch (cyprodinil + fludioxonil, 9 + 12), Captevate (captan + fenhexamid, M3 + 17) at 3.5 to 5.25 lb 68WDG/A, or Elevate (fenhexamide, 17) at 1.1 to 1.5 lb 50WDG/A.