Late blight has been reported on potato on Long Island. This is the first report of late blight in the region to date. Potato and tomato growers should scout their fields on a regular, if not, daily basis and initiate their regular preventative fungicide programs if not already done so.
June 21, 2014 Andy Wyenandt
Vegetable Disease of the Week – 6/21/14
Downy mildew sporulating on the bottom side of an infected collard leaf.
Note the white spore masses.
June 21, 2014 Andy Wyenandt
Vegetable Disease Briefs – 6/21/14
- Basil downy mildew has been reported in New Jersey. With current weather conditions all basil growers should scout on a daily basis and taking appropriate preventative measures.
- Cucurbit downy mildew has been reported on cucumber as far north as central North Carolina as of 6/20. To track cucurbit downy mildew in the US please visit http://cdm.ipmpipe.org/
- No late blight has been reported in the region. Late blight has been found as far as North Carolina to-date. To track late blight in the US please visit http://usablight.org/.
June 21, 2014 Andy Wyenandt
Vegetable Disease Update – 6/21/14
Cole Crops
Downy mildew and Alterneria were confirmed on collard greens this past week. Current weather conditions are ideal for the development of both diseases on all cole crops as well as other crops.
Symptoms of downy mildew on cole crops include the production of white spore masses only on the undersides of infected leaves. The tops of leaves will develop slightly chlorotic (i.e., yellow) spots on the upper leaf surface that become papery in texture.
Alternaria typically starts out as small pinpoint spots on infected leaves that enlarge up to 2 inches. Lesions will become tan, brown or black and may have concentric rings and leave ‘shot holes’ in leaves.
Control of both diseases begins with regular scouting and preventative fungicide programs. Control of downy mildew is best with downy mildew specific fungicide such as Presidio (fluopicolide, 43) at 3.0 to 4.0 fl. oz 4SC/A, or Revus (mandipropamid, 40) at 8.0 fl. oz 2.08SC/A, or Zampro (ametoctradin + dimethomorph, 45 +40) at 14.0 fl. oz 4.38SC/A included in tank-mix with chlorothalonil (M5) at 1.5 pt/A. A phosphite fungicide (FRAC group 33) such as Prophyt, Rampart, or K-Phite can be included to also help control downy mildew. For control of Alternaria, apply chlorothalonil (M5) at 1.5 pt/A alone, or tank-mixed with a FRAC code 11 fungicide such as Quadris (azoxystrobin, 11) at 6.0 to 15.5 fl. oz 2.08F/A or Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 fl. oz 20EG/A, or Fontelis (penthiopyrad, 7) at 14.0 to 30.0 fl. oz 1.67SC/A.
June 13, 2014 Andy Wyenandt
Basil Downy Mildew Confirmed in New Jersey 6-13-14
Basil downy mildew has been reported for the first time this season near Millville, NJ in potted Thai and Cinnamon basil plants being sold at big box stores, as well as in sweet basil located in grower field. All basil growers in New Jersey should scout their fields on a daily basis. [Read more…]
June 9, 2014 Andy Wyenandt
Vegetable Disease Update – 6/9/14
Potato
Black Leg – Black leg is caused by Erwinia spp. which also cause ‘soft rots’. The bacteria which lead to the aerial phase of Blackleg are soil-borne (originate from old crop debris) and spread by rainfall, overhead irrigation and wind. The aerial phase of Blackleg does not originate from decaying seed pieces. The bacterium can enter the plant through wounds created by cultivation or through stems damaged by blowing wind, sand or hail. Dense canopies, warm weather and prolonged periods of leaf wetness favor the spread of aerial Blackleg. Fortunately, the disease rarely extends below ground and only causes dieback of stems over time. Symptoms of the aerial phase of Blackleg first appear as an irregular, water-soaked ‘green’ decay on stems that turns light-brown to black over time. Hot, dry weather will cause infected areas to dry out and become brittle. Do any cultivating when plants are dry, cultivating in the presence of dew or wet plants may help to spread the bacterium around.
