It is only July, and 2016 has already been an interesting season. The cool and wet May has produced lots of foliar and vascular diseases. We have seen cedar-apple rust for the first time in a few years. Oak leaf blister has been evident all over the Denver Metro area. Fireblight in Apples, Crabapples, and Pears got started early, and is now making many of our wonderful ornamental trees rather unsightly.
If that wasn’t enough, the abnormally high temperatures of June gave rise to massive insect populations of aphids, mites, leaf hoppers, and scale. We are now concerned that the ample moisture of April and May, combined with the high temps of June, will result in high populations of Japanese beetle showing up throughout July and August. We have already had our first reports of a few early Japanese beetle adults seen in Cherry Hills Village and Englewood.
It will be important to use all our available tools to deal with Japanese beetles this season. Good monitoring will be vital to identify problem plants and areas. Soil treatments later in the summer will help to reduce the over-wintering population of grubs in the soil. These insects are difficult to control, and have massive appetites. Japanese beetles have a taste for so many plant species that landscapes can quickly be overtaken by a hungry population.