Andy Wyenandt

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.

• Basil downy mildew has been reported in New Jersey. All growers should be scouting on a regular basis and applying protectant fungicides.
• Late blight was reported on potato in northern North Carolina near the Virginia border on this past week. There have been no reports of late blight in the region to date. To track late blight in the US please visit http://usablight.org/
• Cucurbit downy mildew has been reported on cucumber, butternut, acorn, and yellow summer squash as far north as central South Carolina. To track the progress of CDM in the US please visit http://cdm.ipmpipe.org/
• The first reports of bacterial leaf spot are coming in on pepper and tomato.
• Black leg has been reported in potato in southern New Jersey.