Collection and removal of diseased needles on the ground around individual trees may reduce the severity of infection the following year. Copper fungicides are suggested for control such as Junction, Kocide, Camelot, Bonide Liquid Copper Concentrate, and Monterey Liqui-Cop. It may take multiple years of application to bring the disease under control. It is a good idea to spray adjacent susceptible pines. Make sure all needles are thoroughly covered with the fungicide. Two fungicide applications in mid-May and mid- to late-June provide a more complete and dependable control. There is some risk in a single application because susceptible older needles are not protected in late May. A single fungicide application in early June normally will protect foliage from infection. Some copper-containing fungicides can be used for control of Dothistroma needle blight. If the tips of branches are dead and the needles on these branches are shorter than normal, suspect this disease. This disease results in the death of the entire needle, not just the tips. This disease normally kills tips of branches when the needles are about half grown in the spring. Tip blight, another disease, can affect Austrian, Ponderosa, Scots, and Mugo pines, but Austrians are most susceptible. Ponderosa pine also is susceptible to brown spot, but Austrian pine is resistant. Brown spot ( Scirrhia acicula) looks much like Dothistroma but affects primarily Scots pine. Though less common this spring, there can be other causes of yellowing needles. This also is very common this year likely due to the extreme cold we had on December 18.
Winter desiccation can cause these same needle-yellowing symptoms, including banding, but does not exhibit the black fruiting bodies. Needle blight is most serious on Austrian and Ponderosa pines and also can affect Mugo pines. The black fruiting bodies have erupted through the surface of the needle. This fungal disease causes the tips of needles to turn yellow, and yellow to tan bands to form along the needle. If you are having problems with the needles on pines turning yellow, check for Dothistroma Needle Blight ( Mycosphaerella pini) as it has been very common this spring.
0 kommentar(er)
