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UT Extension questions and answers: Common questions about trees

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What is that web-looking thing in my oaks, hickory and maples?
I’ve seen lots of these in my travels through the county. The web-looking thing is created by the fall webworm (hence the name) as part of its life cycle. It defoliates the tree to a certain extent, but rarely endangers the growth of the tree otherwise. Also, we see a rather unsightly “web” that certainly takes away from the beauty of these majestic landscape monuments.  
Control is futile, unless the entire tree can be treated. I suspect most homeowners don’t have the necessary equipment for this. Webs may be pruned from branches that can be easily reached. If the webworm survives, it will fall out of the web and overwinter in the ground below the tree. Yes, it’ll wait there until next year as part of Mother Nature’s plan.
Why are my trees losing leaves this time of year?
Even though we’ve gotten some spotty rain as of late, our trees are still under stress from last year’s dry summer – what?! Of course, trees have a tremendous root system to provide water and nutrients from the soil for optimum growth. During the growing season, even without adequate rain, trees will continue to photosynthesize, but at a slower rate. Consequently, the leaves transpire more moisture than the roots are taking in. So, then we get the yellowed leaves that eventually dry up and fall off.
What can be done? Pray for rain so the trees can “catch up.” In home plantings of smaller trees, a five-gallon bucket with a small hole in the bottom can be placed near the tree so a small amount of water is added to the soil over a longer period of time. Maybe, just maybe, that will help some.
What are these spots on my apple tree leaves?
There are several diseases that can, and will, infect apple tree plantings, if the environmental conditions are just right for them. What I’ve seen lately is cedar-apple rust. The name indicates that both the cedar tree and apple are both culprits – they are co-host to this rust disease. The disease first appears on apple leaves as small greenish yellow spots which gradually enlarge, changing to orange-yellow and becoming surrounded at the border by concentric red bands. Cedar leaves are infected during summer months, and by June the following summer, small greenish brown swellings appear on the upper or inner foliage surface. These swellings en-large and by autumn appear as chocolate-brown, somewhat kidney-shaped galls. Each gall is covered with small circular depressions. The somewhat kidney-shaped galls vary from 1/16 of an inch to over two inches across. The next spring, in moist weather, the pocket-like depressions in the galls put forth orange telial horns. Telial horns are a gelatinous material that swells immensely. A gall covered with telial horns may reach the size of a small orange.
Control? Get rid of cedar trees within half a mile of your apple trees. Probably not practical, so start on a scheduled fruit spray schedule, which in-clude fungicides and insecticides for control of more stuff too! Proper annual pruning will keep the trees “open” in the middle and improve air circulation and sunlight penetration to promote rapid drying after rains and dew. 
Call the UT Extension office at 989-2103 for more information about these or other topics.

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