UMass Extension Landscape Message May 17, 2013
From the Southeast Region (Hanson) report:
"...squirrels were observed biting off the buds on rhododendrons and clipping small branches on Corylopsis spicata to eat the developing seedpods."
"Impatiens downy mildew (IDM) was diagnosed on Impatiens (walleriana) in landscapes in Massachusetts for the first time in 2011 and devastated plantings in 2012. Over the past several weeks, IDM was confirmed in greenhouses in four counties in Michigan and in surrounding states. In each case, the disease was widespread within the greenhouse and losses were nearly 100 percent. DonÃ¢ÂÂt get caught and have to replace plants this season. All Impatiens walleriana including double, mini and Ã¢ÂÂFusionÃ¢ÂÂ are susceptible. New Guinea impatiens (I. hawkeri) and SunPatiensÃÂ® and all other garden plants are not affected. Plant alternative shade plants this spring such as New Guinea impatiens, SunPatiensÃÂ®, coleus, begonias (lots of types), torenia, lobelia, hypoestes and iresine.
The first signs of IDM are leaves that are slightly yellow or off color (not to be confused with lack of fertilizer). As the disease progresses, the undersides of the leaves will have white-colored, powdery-like spores. Sometimes it is difficult to see the spores without a magnifying glass. Eventually the leaves and flowers will drop off of the plant, and leave bare stems with only a few tiny, yellow leaves remaining. Downy mildew can be spread long distances by wind currents, water splash (overhead irrigation included) or by the movement of infected plants.
Infected plants should be pulled, bagged and disposed of. Do not compost. The area should not be replanted with susceptible impatiens species, but can be replanted with any other plants. Fungicide sprays are not recommended in landscapes and home gardens! It is expected that IDM will be a recurring problem. Impatiens downy mildew oospores from infected plants overwinter in the soil and IDM can infect wild impatiens (jewelweed, I. capensis). A comprehensive fact sheet is available at: http://extension.umass.edu/floriculture/fact-sheets/impatiens-downy-mildew -Tina Smith, UMass Extension"