Field and Garden: Still time for many vegetable crops

A friend from Indiana called last week, and I patiently listened as he boasted about his thriving garden. “I picked my first cucumber today,” he said, “and my tomatoes look tremendous.”

My experience this year has been quite the opposite.

My potatoes died after heavy rain left them standing in water for several days.

Other vegetables – corn, cucumbers, and zucchini – didn’t emerge at all and had to be replanted. They are growing now, but way behind in development compared to last year.

I’m not ready to give up, though. I planted green beans last week, and there’s still plenty of time for lettuce, radishes, beets, and turnips too.

With two and a half months until frost, I intend to make the most of the remaining growing season.

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Here are some questions that I’ve recently been asked:

Q: What’s wrong with my plum trees? The fruit is abnormally large and hollow.

Plum pocket is a fungal disease which causes unripe plums to grow abnormally large within a month or two after blooming.

This year’s cool, wet weather likely contributed to the outbreak of the disease, which infects wild plums and American plums more than dessert plums.

Plum pocket spoils the fruit but doesn’t harm the trees.

To prevent recurrence next year, it’s recommended to remove and dispose of infected plums before they become covered with spores.

If plum pocket destroys most of the fruit for several years in a row, applying fungicides before bloom can help manage the disease.

Q: What insect is eating the leaves on my rose bushes?

Likely culprits are one of two types of sawfly larva, either roseslug or bristly roseslug. Both types feed on the soft tissue of leaves, leaving the harder veins intact, creating a skeletonized appearance.

Roseslugs have just one generation per year. By mid to late June, they’ve dropped from the leaves and burrowed into the soil. They won’t do any more damage until next year.

In contrast, bristly roseslugs may have as many as six generations per year.

Check the undersides of the rose leaves. Male bristly roseslugs are pale green and covered with many hair-like bristles all over the body. The females are shiny black with yellowish-orange markings on the body.

For small infestations, you can remove the larvae by hand or wash them away with a strong spray of water.

If needed, you can also use Spinosad, a natural substance made by a soil bacterium, to kill the larvae.

Q: The leaves of my maple tree are covered with small bumps. What are they?

Several types of mites can cause the formation of galls on the leaves of maple and other trees species as well.

As they feed on leaf surfaces, the mites release chemicals that interact with plant hormones, causing abnormal cell growth.

The abnormal growth becomes a gall, which gradually encloses the mite. The gall continues to grow as the mite feeds.

In most cases, the galls do not harm the tree, and treatment is unnecessary.

If you have questions about your lawn or garden, please contact me in the Extension office (652-2581, jeff.gale@ndsu.edu.