For over a decade, basil downy mildew (BDM) has caused significant losses in basil grown in organic and conventional field and greenhouse production across the United States. At the time of its introduction, there were very few fungicides labeled for its control making it nearly impossible to grow a successful crop in many areas of the country. [Read more…]
October 12, 2021 Andy Wyenandt
ALERT – Alternaria leaf spot active on fall cole crops.
Alternaria leaf spot has been reported on broccoli this week. Weather conditions for the development of both diseases has been ideal. Preventative control is recommended and growers should scout and apply protectant fungicides on a regular basis. Note, if Downy mildew is present use downy mildew specific fungicides in conjunction with fungicides for Alternaria leaf spot control. For more information on controlling Alternaria and Downy mildew, please see the 2020/2021 Commercial Vegetable Production Recommendations.
Alternaria leaf spot infection. Note the yellow halo around each spot. Under ideal conditions black concentric rings will develop within each spot. These rings are the conidia which are then spread causing new leaf spots to develop.
Symptoms of downy mildew on infected chinese cabbage leaf. Note the irregular chlorosis and browning of upper leaf surface. Under ideal conditions the pathogen will produce white spore masses only on the undersides of the leaf.
February 20, 2018 Andy Wyenandt
Fungicide resistance management guidelines for cucurbit powdery and downy mildew control in 2018
Extension specialists in the mid-Atlantic and Northeast regions have put together new guidelines for cucurbit powdery and downy mildew control. These new guidelines list all recommended fungicides and their efficacy ratings for controlling both diseases based on recent fungicide efficacy trials. Also included in the new FRAC table are notes on fungicides where resistance has been detected in the region. The new FRAC table can be downloaded for FREE on American Phytopathology Society’s Plant Health Progress website.
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.
September 12, 2013 Andy Wyenandt
Vegetable Disease Briefs – 9/13/13
There have been no new reports of Late blight.
Downy mildew has been found in turnip greens this past week. The expected rainfall and cooler temperatures to follow in the upcoming week make conditions favorable for downy mildew development across many crops.
Asparagus – Summer foliar diseases in Asparagus have been reported. With the cooler weather and all the rain we’ve have been experiencing on and off all summer disease pressure in asparagus is higher than normal. See article from 9/4/13 for more information.
Basil downy mildew remains active – All basil growers should scout on a daily basis and should add a labeled downy mildew specific fungicide to their weekly fungicide program. Phosphite fungicides (FRAC code 33), such as Prophyt, K-Phite, and Rampart have shown the best efficacy in trials at RAREC. Actinovate (OMRI- approved) is also labeled for downy mildew control. Please remember, all abandoned basil fields should be worked under immediately after last harvest to kill the foliage! Abandoned fields left unattended after use will only serve as a source of inoculum for other fields.
Cucurbit downy mildew and powdery mildew remains active in New Jersey.
April 28, 2013 Richard Buckley
Take Off Your Rose Colored Glasses
Downy mildew was identified in Knock Out® rose samples submitted to the Plant Diagnostic Lab from a south-Jersey nursery this week. Knock Outs®, which have few problems, have been a favorite in New Jersey landscapes in recent years. Unfortunately, it seems this plant has met its Achilles’ heel.
Downy mildew on Double Knock Out® rose. Photo: Sabrina Tirpak, Rutgers PDL
