Clinic Update-September 6

Raspberry with stinkbug injury. Photo by Sandye Davis.

Tomato with stinkbug injury. Photo by Sandye Davis.

Along with the hot, dry weather of the past month, we saw an overall decrease in sample submissions to the clinic, but an increase in submissions with damage related to the weather. Samples with leaf scorch and needle scorch included maple, spruce, and dogwood. From areas of the state with more rainfall, we did see some tree samples with leaf spot diseases. Guignardia leaf blotch was observed on horse chestnut and a Bradford pear sample was submitted with Phyllosticta leaf spot. With wet fall weather, we expect leaf spot diseases to become more prevalent in coming weeks.

Some of our ornamental sample submissions have been the result of overwatering to compensate for the drought or irrigation leaks. Submissions included chrysanthemums with Fusarium and Pythium root and stem rots, as well as rhododendrons and a white pine with Phytophthora root rot. Other submissions included Magnolia with tulip tree scale and rose with rose-rosette virus. Turf samples included zoysia with heavy chinch bug infestation and Rhizoctonia infections as well as fescue with a heavy rust infection.

Several peach samples were submitted with brown rot. Infected fruit eventually shrivel up and develop a fuzzy coating of fungus. The disease is common in Missouri and in many cases it seems fungicides have not been completely effective due to poor sanitation the previous year (removal of infected fruit) and timing of fungicide applications. A homeowner’s fruit tree spraying schedule information sheet can be accessed at: http://extension.missouri.edu/explore/agguides/hort/g06010.htm Stinkbug damage has alsobeen submitted on tomato, pepper and raspberry. Other common problems on tomato have included sunscald, yellow shoulder and blossom end rot. Finally, we have had some samples with high spider mite infestations. While recent cooler, wet weather may help get mites under control, information is available on managing spider mites at: http://extension.missouri.edu/xplor/agguides/pests/ g07274.htm

We look forward to receiving your samples in the clinic. Your sample submissions help us to determine what plant problems are occurring around the state. While we are often not able to diagnose plant problems from a description of the problem over the phone, you can call us if you have questions about what material to submit for a quick and accurate diagnosis.

Simeon Wright
and Sandye Davis,
Plant Diagnostic Clinic
573-882-3019