Boone County Purdue Extension, 1300 East 100 South, Lebanon, IN 46052 cemanuel@purdue.edu 765-482-0750

Early Summer Garden Tips

With so many first-time vegetable gardeners this year I want to provide some tips on issues to look out for and practices to help your garden during the early portion of summer.

Tomatoes: Tomatoes are the most popular vegetable crop grown in Indiana home gardens. For those who have not raised tomatoes before, there is a risk of the fruit developing cracks as it develops. There are some pests that may cause this however this usually occurs when we have alternating dry and wet periods during fruit set. As the plant takes up water, the fruit swells, then shrinks as the plant dries out, resulting in cracks. To mitigate this, once fruit begins to develop, provide supplemental water to help maintain soil moisture. If you have not done so, using a mulch to help retain moisture can also help. The cracks themselves do not make the fruit unsafe to eat once you cut them out however the wounds do provide an avenue where other diseases may enter.

In-season fertilization also helps tomatoes. Ideally, sidedress about 1/3 pound of actual nitrogen (N) per 100 foot of row three times during the growing season:

  • One to two weeks after the first fruit set
  • Two weeks after picking the first ripe fruit
  • Six weeks after picking the first ripe fruit

It is important not to over-fertilize tomatoes. Too much fertilizer can result in a plant with great vegetative growth but no fruit. Basically the plant receives a lot of fertilizer and doesn’t realize that the growing season may be ending and never begins its reproductive cycle.

Sweet Corn: Sweet corn also benefits from nitrogen fertilizer during the growing season. For intense management you can apply fertilizer as many as three times however the most important application is to sidedress 1-1.5 pounds of N per 100 feet of row at growth stage V8. V8 means when you can see eight leaves on the plant.

Sidedress means placing nitrogen in a band near but not in the row where the plants are growing. Use the handle of a garden tool such as a hoe or shovel to create a two-inch deep channel or groove about two inches away from the row. Place your granular fertilizer in the channel and cover it up. For liquid fertilizer, dribble it into the channel. It is best to apply either when the soil is moist or before rain is expected. For best results, place N on each side of the row. If your tomatoes are spaced far apart, create a ring around the base of the entire plant.

Cucurbit Pests: Cucurbits include squash, cucumber, melons, cantaloupe, pumpkins, and other similar crops. While most cucurbit diseases show up later in the season, the pests that cause them should be controlled starting now.

Squash bugs begin appearing in late June. They feed on all parts of the plants – leaves, stems and fruit. When they feed, they inject toxins from their saliva into plants which damage tissue. While noticeable on leaves, the most serious damage occurs when they either destroy a stem or damage fruit.

Squash bug adults are difficult to control so your focus should be on the nymphs. To see if you may have a possible squash bug problem, look for clusters of copper-colored eggs on plant stems or the underside of leaves. If you have more than one cluster per plant be prepared to control them once they begin hatching. While you may apply pesticides, so long as you are willing to regularly monitor your plants, you can usually control them by knocking the nymphs off into a bucket of soapy water. Squash bugs can be a serious pest of all cucurbits but particularly squash, pumpkin, melon and cucumber.

Squash Bug Larva
Squash Bug Adult

Cucurbit growers need to be alert to the presence of striped cucumber beetles. These are very distinctive insects with black heads and yellowish bodies with three black stripes running down their wing covers. They can sometimes cause enough damage by feeding on leaves and stems to result in problems however often the most serious damage shows up later in the growing season as striped cucumber beetles carry and transmit bacterial wilt, a devastating plant disease.

Striped Cucumber Beetle

It is impossible to treat bacterial wilt once a plant is infected. The most effective method is through control of cucumber beetles. Control recommendations vary with each individual crop. For additional information refer to Purdue Extension publication E-95-W, “Managing Striped Cucumber Beetle Populations on Cantaloupe and Watermelon” by Purdue Extension Entomologist Rick Foster. It is available online at: https://extension.entm.purdue.edu/publications/E-95/E-95.pdf

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