Connecticut State The Connecticut Agricultural Experiment Station

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--Updates, Alerts, and News from the PDIO--
 July 2013
-Begin to Scout for Impatiens Downy Mildew-
Last year impatiens downy mildew was confirmed in many residential and commercial landscapes throughout Connecticut. This disease is caused by Plasmopara obducens, a fungus-like organism (also called a water mold or oomycete). All cultivars of the common garden impatiens, Impatiens walleriana, are susceptible. However, New Guinea impatiens appear to be tolerant to downy mildew. This pathogen does not infect cucumbers or squash (or any vegetable) or any other common bedding plants. The downy mildew pathogen is spread by infected plants, water/rain, and wind. It can splash from plant-to-plant within a landscape bed or can be airborne and travel over much longer distances. Early symptoms of downy mildew begin as light-green yellowing, mottling, or stippling and often go unnoticed. These symptoms are often mistaken for nutrient imbalances or spider mite infestations. Advanced symptoms include stunting of whole plants, leaves, and flower buds, downward curling of leaves, wilting, plant collapse, and severe defoliation that results in bare, leafless stems. 

Downy mildew is particularly destructive under moist conditions and cool nights--just the weather we have recently been having throughout the state.

Stunted new growth
Impatiens downy mildew--note stunted plants with distorted leaves.

downy mildew of imapatiens with twisted leaves
Subtle chlorosis and twisting of leaves of impatiens with downy mildew.

Any suspicious impatiens samples should be sent or brought to The Plant Disease Information Office for examination and diagnosis as soon as possible.

IF downy mildew is diagnosed on your plants, all infected plants should be dug (roots included) and placed into municipal trash, when acceptable. Infected plants should not be composted.

If you have any concerns or want more information about this destructive disease, please call The Plant Disease Information Office at 203.974.8601.

 
July 2013
-Late Blight Reported in MA-
-Scout for Late Blight of Tomato and Potato-

Late blight was confirmed in Franklin County, MA on tomato on 11 July 2013 and in Erie County, NY on tomato on 10 July 2013.  The recent weather has been very favorite for this disease of tomato and potato, so it is important to scout for this destructive disease. It is very important for commercial growers and home gardeners to be on the lookout for late blight in their fields and community or backyard gardens.  Information on this important disease can be found in the fact sheet Late Blight of Tomato and Potato in Connecticut--2012 

Any suspicious tomato or potato samples should be sent or brought to The Plant Disease Information Office for examination and diagnosis as soon as possible.