Field and Garden: Now is the time to deal with dandelions

Drive by my house and you’re likely to say to yourself, “There’s a lawn that has some issues.”

Dandelions, thistles and a host of other weed species have gained a large foothold in my yard.

Getting them under control is going to take some work.

The good news is there is no better time to get started than now, during the month of September.

Dandelions and thistles are getting ready for winter by transporting nutrient reserves to their root systems.

We can take advantage of this phenomenon.

Herbicides that are applied now and absorbed by the leaves will be transported to the roots right along with the nutrients, and the weeds will be killed.

Chemical products containing a mixture of 2,4-D, MCPP and dicamba generally give very good results.

Examples of these products include Trimec, Weed-B-Gone and Weed-Out.

It may be tempting to try to kill two birds with one stone and apply a ‘weed and feed’ fertilizer.

After all, Labor Day weekend is also a great time to fertilize lawns.

However, weed and feed fertilizer is not the best choice at this time of year.

To be effective, the herbicide-containing granules must stick to the leaf surfaces of the weeds. For various reasons, that doesn’t always happen.

A better approach is to apply fertilizer, one that contains at least 20 percent nitrogen and 10 percent potash, and then go back and spot spray weeds with herbicide.

You’ll save money and minimize herbicides in the environment.

As always, it’s essential to read and follow label instructions.

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Here are two questions that I have encountered recently:

Q: Why are the leaves on my Honeycrisp apple turning yellow?

A blotchy pattern of yellow is common on the leaves of young Honeycrisp apple trees in July and August.

The symptom is caused by the accumulation of large starch granules in the leaves. The granules reduce photosynthesis and the production of chlorophyll.

No treatment is necessary. The condition looks worrisome, but it will have no effect on long-term productivity.

In general, the phenomenon gradually disappears as the tree matures and begins producing more fruit.

Q: How can I control webworms on my chokecherry trees?

Fall webworms attack more than 100 species of deciduous trees, including chokecherry.

The pest is noted for the webbed, tent-like structures that it builds around tree branches to protect itself from birds and other predators.

When all the leaves inside the “tent” have been consumed, the larvae gain access to new leaves by enlarging the structure.

Fall webworms rarely cause serious damage to large trees. However, several years of feeding can weaken small ornamental trees.

It’s difficult for insecticides to penetrate the web and reach their target.

The best solution for controlling webworms is to knock the web out of the tree with a rake.

Once the webbing is destroyed, the larvae can be sprayed with the bacterial insecticide Bacillus thuringiensis.

If you have questions about your lawn and garden, please contact me in the Foster County Extension Office (652-2581, jeff.gale@ndsu.edu).