Poor branch structure on Austree

Question:

I have two Austree willows (a hybrid between a Globe willow and something else); they were four feet tall when planted, and now are about 30 feet tall and about 30 feet across at the dripline. The problem is that all the branches came out from the trunk at four feet. There is not one branch that forms the trunk above this point. As a result, there's a "bowl" that has developed at the center of these branches. The bowl is an inch deep and 6-8 inches across in the center. It is full of water, dead leaves, etc. Each branch is about 8 inches or more in diameter, so it would be drastic to prune. Any suggestions? Is it OK as is?

Maria W.
Bosque Farms

Answer:

You have indeed described white grubs. These are the larvae of several types of beetles. The most common are the larvae of the May and June beetles that fly around lights at night (in May and June. These grubs feed on the roots of plants causing significant injury.

There are several controls for grubs. You will often see milky spore disease (a bacterial disease of some grubs) recommended for controlling grubs. This is effective in controlling Japanese beetles but not effective in controlling the larvae of May and June beetles that are common here. A more effective non-synthetic chemical method of control involves application of entomopathogenic (insect attacking) nematodes such as Heterorhabditis and Steinernema species. There are also several synthetic chemicals that are effective. These include imidacloprid, isazophos, isofenphos, and others. Less hazardous to humans and pets are the insect growth regulators which are also effective. However, the time to apply these chemicals is drawing to a close because the grubs will soon retreat deep into the soil and pupate before emerging as beetles in the spring. When using any pest control material (synthetic or organic), it is important to read, understand, and follow the label directions.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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