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Dieback in Cherry and Other Stone Fruits and Crabgrass and other Annual Weed Grasses
By John Fulton

[July 26, 2016]  Dieback in Cherry and Other Stone Fruits - Many have been concerned with cherry, plum, and even peach trees showing dead twigs and branch tips this year. It looks like fire blight has affected trees in this group, and even the ornamental trees in the stone fruit group. However, fire blight is confined to a different fruit group containing apples and pears. Instead, the cherry trees are most likely infected with brown rot.

Brown rot is caused by a fungus, where fire blight is caused by bacteria. Both diseases cause damage by blighting blossoms, killing shoots, and causing branches to die because of cankers which stop the flow of sap to branch ends. Brown rot also causes direct fruit damage, which can result in “mummies.” These are dried, shrunken fruit which clings to the trees. This fungus lives in the mummified fruit, and in the cankers it forms on limbs and twigs.

Removing the mummies, and pruning out the diseased wood are the starting points for some control. Pruning is best done during dormancy, and disinfecting equipment between cuts is recommended. Sprays with a preventative fungicide, such as captan, are recommended when blossoms open, at full bloom, and when blossom petals fall. Be sure to check pesticide labels for appropriate use on fruit trees, and combination products with insecticides (such as home fruit tree sprays) should not be sprayed during bloom to protect bee populations.

Crabgrass and other Annual Weed Grasses

Crabgrass and other annuals grass weeds can be seen about everywhere. Annual grasses which are common include the different crabgrasses, foxtails, and barnyard grass. They have been the most asked about items this past week. They will die with the first frost, so treatment is not available, or recommended, in the fall. The only exception to available treatments is the use of glyphosate (Roundup is one trade name) in areas where there are no desirable plants. Make a note of where these grasses are, and an overseeding to thicken up the grasses you want there may help crowd out the annuals. Preventative treatments may also be applied in the spring (around April 1 depending on soil temperatures) to kill the germinating seeds. As many have found out, a second treatment about June 1 is also necessary since the products only last six to eight weeks. The short life of preemergence treatments actually gets shorter in extremely wet years. These grasses are extremely troublesome this time of year as they stay wet and tend to clump on the bottom of mower decks, but there isn’t a cure at this time – other than the continued mowing.

 Keep mowing when the grass or weeds dictate mowing. The rule of thumb is to remove no more than a third of the leaf blade at any one time. This means that if your desired mowing height is 2 inches, you should be mowing when the grass gets 3 inches tall. The summer slump came early this year, but has quickly subsided due to all the rain. Except for the couple week break, we have been on the program of mowing every three days.. It’s amazing what rain will do.

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]