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Published August 26, 2009, 12:45 PM

Pruning vines promotes ripening

If your melons, pumpkins, or tomatoes that have set on enough fruit to supply your needs for the year, it is OK to prune off the ends of the vine.

By: Kyle Schulz, Master Gardener, Wadena Pioneer Journal

If your melons, pumpkins, or tomatoes that have set on enough fruit to supply your needs for the year, it is OK to prune off the ends of the vine. Pruning the ends of vines in these plants is a great way to encourage them to ripen their fruit and quit growing. The energy in the vine goes into finishing the fruit on the vine rather than continuing to grow and produce more flowers and fruit. So evaluate your crop and decide if your vines have enough produce on them and if you want it to ripen before frost, pruning will help to accomplish this.

Key to good corn

Sweet corn is the vegetable of desire in the month of August. The keys to high quality sweet corn are rapid growth, adequate soil moisture and nutrients, and harvesting at optimum maturity. While our weather has not given us conditions that have favored the rapid growth of corn this year, and the crop is a little later than usual, we are now enjoying this summertime tradition.

The level of sucrose (sugar) in the kernels determines the corn’s sweetness. In most cases sucrose is rapidly converted to starch if corn is not cooked, frozen, or refrigerated just after it is harvested. It is the starches that make corn less tender and less sweet. On a corn seed packet you may find a short abbreviation which describes the type of sweet corn. Sweetness is described as follows:

• “Normal” sweet corn (su) kernels contain moderate amounts of sugar (8-18 percent) that vary with the variety of corn. The sugar is converted to starch rapidly. Normal sweet corn can be planted earlier because the soil temperature needs to be only 50 degrees to germinate.

• “Sugar-enhanced” (se, se+, EH) has increased sugar levels (30-35 percent). The genes in this type modify the su gene, resulting in increased tenderness and sweetness. Also the conversion of sugar to starch has been slowed. Sugar-enhanced corn needs a soil temperature of 55-60 degrees to germinate.

• “Super-sweet” or “Xtra-sweet” (sh2) has more increased sugar levels (40-50 percent). This gene (sh is short for Shrunken) creates greatly increased sweetness and slow conversion of sugar to starch. The dry kernels or seeds of this type are smaller and shriveled. These Xtra-sweet varieties require warmer soil temperatures of at least 60 degrees to germinate. One way to increase the soil temperature is to use black plastic (which will raises soil temperature by about 10 degrees) and poke holes where each seed is planted.

Corn is monoecious (mon-ee-shuss) which means there are both male and female flowers on each plant. In corn the male and female flowers are on different locations — the male flowers form a tassel at the top of the plant. The female flowers are at the junction of leaves and stem. They consists of hairs (silks) enclosed in the husks of what will be ears. The silks are pollen-receiving tubes. Wind-blown pollen from the tassels falls on the silks below. Each silk leads to a kernel, and pollen must land on all silks for the ear to fill completely with kernels. Kernel “skips” (ears only partly filled out with kernels) are often the result of poor pollination.

Because the wind pollination of corn is very important, block plantings of 3 to 4 short rows will pollinate more successfully than one or two long rows. Most corn varieties will cross-pollinate readily. To maintain desirable characteristics and high quality, Xtra-sweet and standard sweet corn should be isolated from each other. A distance of 400 yards or planting so that maturity dates are one month apart is necessary to insure this isolation. White and yellow colored corns will also cross-pollinate, as will field corn, popcorn, and ornamental corn.

The best time to harvest corn is the “milk stage” when the ears are fully formed but not ripe. You can determine this by looking at the silks, husks and kernels. The silks should be brown and dry. This is about 3 weeks (18-24 days depending on the weather) after the silks appear. The husks should hold tightly to the ear, and the kernel should produce a white milky fluid when pierced. Super-sweet kernels will produce a clearer liquid when ready. Because of the clearer liquid, these types do not make as nice a creamed corn product. Corn should be harvested in the cool morning hours and if not used immediately, should be kept on ice or stored in a cool place at 38 degrees to ensure quality flavor and tenderness.

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