![]() ![]() If infection occurs during a year in which fungicide has not been applied, and is severe enough to warrant control, then fungicide can be applied the next year with confidence that good control will be obtained. Monitor susceptible pines for symptoms of infection each year. Focus on getting good coverage on the lowest 6-8 feet of the canopy.Īnnual applications of fungicide are not always necessary to control this disease. Spray applications to large trees are difficult, so if you don’t have the equipment to reach the top of the tree that’s OK. ![]() The first application is usually done in mid-May and protects last year’s new growth. The second application, which protects this year’s new growth, is made after new growth is complete and needles are fully expanded usually around mid- to late June. Look for liquid or fixed copper formulations, such as Bonide Copper Fungicide, Monterey Liqui-Cop, Southern Ag Liquid Copper Fungicide and any other copper fungicide labeled for use on evergreen trees. Many formulations of these products are available from a variety of manufacturers, just make sure pine trees are a labeled site for the product you buy. Read and follow all label directions carefully before application. Copper fungicides work well, are very common and can usually be found at most nurseries and garden centers that have a good chemical selection. They also have low human toxicity and low environmental impact. Infection on trees with a history of Dothistroma can be significantly reduced by making two fungicide applications. Prune out dead branches in pines to reduce fungal innoculum. Frequent wetting increases the potential for needle infections. A flat, even layer is ideal, pulling the mulch back slightly so it does not lay against the tree’s trunk.Īdjust landscape irrigation heads so water does not spray on your pine tree’s needles. Maintain a 3-4 inch layer of wood chip mulch beneath trees, but do not mound it up around the tree’s trunk. Promoting overall tree health and vigor goes a long way to lowering a tree’s susceptibility. These areas often have higher natural humidity which promotes needle infection. First, avoid planting susceptible pines in low lying or poorly drained areas. Several management strategies can help minimize Dothistroma’s impact on your trees. Lower branches of trees are most severely infected, due to reduced wind movement and slightly higher humidity levels near the ground, but the entire tree may show symptoms. The fungus grows within these tissues, killing that portion of the needle beyond the lesion. Initially, the tip of the needle dies while the base remains green, but eventually as the disease progresses, the base of the needle also dies and the entire needle drops off the tree. These bands are often bordered by a yellow, chlorotic ring on each side. These spots darken and become brown or reddish-brown then spread to form a band around the needle. Symptoms are first seen as yellow or tan spots on older needles. Symptoms appear about three to four months after infection, usually becoming visible in late fall. During spring’s wet, cool weather, spores are released and spread through wind or rain splash to new needles. Germinating spores enter the needles through natural openings and the infection process begins. A sparse pine canopy, as on this Austrian pine, is often the result of early needle loss due to diseases like Dothistroma.įungal spores develop on dead sections of needles infected the previous year.
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