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Published May 22, 2009, 12:00 AM

Hungry insects leave waxy ooze on trees

Q: I have a pine tree that is oozing a waxy substance. There is so much of it that the rocks beneath the tree are shiny. I also noticed that the branches are covered with little black bugs. They look like they might have wings, but none of them are flying. The tree looks wet from the waxy substance and draws many flies. Do you have any idea what these insects are and how to fix the tree?

By: By Ron Smith, INFORUM

Q: I have a pine tree that is oozing a waxy substance. There is so much of it that the rocks beneath the tree are shiny. I also noticed that the branches are covered with little black bugs. They look like they might have wings, but none of them are flying. The tree looks wet from the waxy substance and draws many flies. Do you have any idea what these insects are and how to fix the tree? (e-mail reference)

A: The insects can be positively identified only by a visual inspection. The insect world is filled with too many lookalike characters to identify from your description. What is oozing is the sap these pests are feeding on because it is a carbohydrate-rich material.

The best way to control them is to visit a garden supply store and see if you can find some Bayer Advanced Tree and Shrub Insect Control. This is Merit (imidacloprid), which is very effective at controlling any plant-feeding insects. Be sure to follow label directions when using this material. It will call for a particular dilution and for the application to go around the base of the tree. Done properly, the effect of this insecticide will last up to 12 months. It needs to be absorbed into the vascular system of the tree so when the insects feed on the sap, they are killed.

It will take two to three weeks before the insecticide kicks in. It depends on the rate of growth of your tree. If you want faster effects, there are a number of insecticides on the market that are direct-kill products, such as those that contain Malathion.

Q: I have a question about a cherry tree I have. I know I can bake the cherries or eat them, but I do not know when to pick them off the tree. I have no idea if I should spray the tree or what else to look for. I also don’t know how to get rid of birds that are eating the fruit. (Spokane, Wash.)

A: The best way to tell if the fruit is ready to be picked is to taste it! It’s a good sign that the fruit is ready when the birds become excited and start invading the tree, but often it is too late for you to enjoy the fruit because the birds eat the fruit in a wink of an eye.

There are a number of harmless approaches to getting rid of the birds. Hang old aluminum pie tins from the branches throughout the tree. Purchase an artificial owl that is stuffed or filled with helium. Other methods include using balloons or rubber snakes to scare the birds away. Use all or any of these tactics well before the fruit begins to ripen.

It’s a good idea not to use any sprays on the fruit unless insect or disease problems become unbearable. I advise you to get a professional arborist to prune the tree early next spring before blooming to maintain the health of the tree.

Q: I have been given a couple of offshoots of a fruiting avocado tree to plant in my yard. Am I likely to get fruit from the offshoots once they are established? Do I need to plant more than one? (Tampa, Fla.)

A: Avocados are self-fruiting. The fruit from a single tree usually will be sufficient. For heavier fruit set, even from fruit trees that are touted as being self-fruiting, the fruit load is increased significantly if another one can be planted nearby, usually within one-fourth mile.


Gardening or houseplant questions can be directed to: Hortiscope, Box 6050, NDSU Dept. 7670, Fargo, ND 58108-6050 or ronald.smith@ndsu.edu

Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations

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