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Cucumbers, muskmelon, watermelon, squash, and pumpkins have separate male and female flowers and rely on pollinating insects- especially bees- to transfer pollen from male to female flowers. Bee populations were small this season. So far, it has been an excellent year for growing vine crops, and there are many flowers to pollinate. If pollination doesn't occur, female flowers start to grow, but produce small fruits that turn yellow or black, dry up and fall off the plant. Incomplete pollination results in fruit that is misshapen or malformed. Because cucumbers have many flowers per square foot, they have the greatest need for pollinating insects, followed by muskmelon, squash, watermelon, and pumpkins.
There are some other insects that can pollinate as well as bees, but bees are the most reliable and consistent. Spraying should be done in late afternoon or night to avoid killing bees. Do not water in the morning when flowers are open and ready for pollinating. Bees will not 'work' in wet conditions. (CWM)
There are a lot of tomatoes set on plants, but they are just sitting there, not turning red. The optimum growing and ripening temperature for tomatoes is 85 to 90F. At temperatures above 100 degrees, tomato plants 'shut down' concentrating on moving water to keep the plant alive. Fruit development slows or even seems to stop. Cooler temperatures--even in the low to mid 90s--will begin the ripening process again.
Tomato flowers abort in hot, dry conditions, so you may notice tomato plants not setting any small tomatoes recently. Again, if temperatures moderate soon, plants will bloom and set more tomatoes that can ripen before a fall freeze. (CWM)
Blossom-end-rot, a brown leathery patch that develops on the flower end of tomatoes, is a physiological disorder--not a disease. It results from a deficiency of calcium in the developing fruit, but a shortage of calcium in the soil is not the problem. When mild, wet conditions prevail, tomato plants produce more top growth than root growth. With sudden hot, dry conditions, the plant must increase root growth dramatically. Leaves sometimes curl and roll inward, and water flows to the leaves to try to keep the plant from wilting. Calcium moves with the water and bypasses the fruit, leading to blossom-end rot. After the plant acclimates by increasing root development, blossom-end rot goes away. Adding extra calcium does little good. Lush-vined varieties are more prone to problems, and early varieties are more susceptible because they produce fruit earlier in the season. Pick off defective fruit to encourage new ones to form. Provide some supplemental watering but don't water in excess because the tomatoes may never increase adequate root development. Heavy fertilization or fertilization with certain fertilizer elements, such as ammonium nitrogen forms, should be avoided since this competes with calcium for root uptake. Blossom-end rot usually disappears in mid to late July. We're running a little late this year, so it should disappear by late July. (CWM)
Soil tests sometimes show a higher pH than we would like, especially from the western half of the state. Sulfur is often recommended to lower pH but this solution is not as clear cut as many people think. Here are some facts to keep in mind.
Free Calcium Carbonate: Some soils have free calcium carbonate, actual particles of limestone mixed in the soil. These "calcareous" soils normally have a pH of 7.3 to 8.5, with 8.2 to 8.3 being most common. In order for us to lower the pH with sulfur, all free calcium carbonate must be neutralized first. A recent soil test showed 6.7 percent free calcium carbonate. One pound of sulfur is needed to neutralize three pounds of calcium carbonate. Assuming 80 pounds for a cubic foot of soil, you would need about 1.75 pounds of sulfur per square foot just to neutralize the free lime. Additional sulfur would be needed to lower pH. Adding this much sulfur to a soil at one time is not recommended.
Not all high pH soils are calcareous. Perform this simple test to see if your soil contains appreciable amounts of free lime. Apply one drop of vinegar to dry soil. A vigorous fizz usually means the soil contains at least 3 percent calcium carbonate. A mild fizz suggests a calcium carbonate of between 1 and 2 percent and a fizz that can only be heard suggests the soil has a calcium carbonate content less than 1 percent.
How Sulfur Works: Elemental sulfur does not lower pH directly. It must first be oxidized to the sulfate form with the result being sulfuric acid. The sulfuric acid produces hydrogen, which acidifies the soil and lowers pH. The oxidation takes place primarily through microbial activity.
Oxidation Takes Time: Microbial oxidation of elemental sulfur takes time and depends on:
- number of sulfur oxidizing bacteria present
- temperature (75-104 degrees optimum)
- moisture content of soil (too wet or too dry will slow down process)
- size of sulfur particles (the smaller the better)
A single sulfur application normally takes at least 2 years for most the sulfur to react and form sulfuric acid. This, of course, depends on the above factors.
So, what do you do about calcareous soils? That will be a topic for next week. (WU)
The first Cicada Killers of the year have appeared. These large (1-1/3- to 1-5/8-inches long) wasps can be seen flying slowly above the surface of the ground. Cicada killers have a black body marked with yellow across the thorax and abdomen. The wings are reddish orange. Although these wasps are huge, they usually ignore people. Males may act aggressively if they feel threatened, but they are unable to sting. Females are able to sting but are so non-aggressive that they rarely do. Even if they do sting, the pain is much less than that of smaller wasps such as the yellow jacket or paper wasp. The cicada killer sting is on par with that of a sweat bee. The Cicada Killer is a solitary wasp rather than a social wasp like the yellow jacket. The female nests in burrows in the ground. These burrows are about the size of a quarter in diameter and can go 6 inches straight down and another 6 inches horizontally. Adults normally live 60 to 75 days from mid July to mid September and feed on flower nectar and sap exudates. The adult female seeks cicadas on the trunks and lower limbs of trees. She then stings her prey, flips it over, straddles it and carries it to her burrow. If she has a tree to climb, she will fly with it. If not, she will drag it. She will lay one egg per cicada and then stuff them into her burrow. Each burrow normally has three to four cells with one to two cicadas each. However, it is possible for one burrow to have 10 to 20 cells. Eggs hatch in 2 to 3 days and larvae begin to feed on the paralyzed cicadas.
Feeding continues for 4 to 10 days until only the outer shell of the cicada remains. The larva overwinters inside a silken case it has spun. Pupation occurs in the spring. There is one generation per year.
Cicada killers are not dangerous, but they can be a nuisance. If you believe control is necessary, treat the burrows after dark to ensure the female wasps are in their nests. The males normally roost on plants near the burrow sites. They can be captured with an insect net or knocked out of the air with a tennis racket during the day. Carbaryl (Sevin) or diazinon may be used for control. (WU)
Anthracnose on Putting Greens 
Anthracnose is rampant on bentgrass and annual bluegrass putting greens throughout eastern Kansas. Frequent rains and high temperatures in early June led to poor vigor of grass plants and ultimately triggered the anthracnose outbreak. As mentioned in an earlier newsletter, the main remedy for anthracnose damage is cultural practices and cooler weather.
Do not continue to use high rates of thiophanate methyl (Cleary's 3336 or Fungo) or azoxystrobin (Heritage) to combat anthracnose. This will cause resistance problems, if it hasn't already. If anthracnose persists, use a combination of propiconazole (Banner) or triadimefon (Bayleton) withchlorothalonil (Daconil and others). Unfortunately, these three products may cause phytotoxicity to bentgrass during hot weather, but may be the only option.
Brown Patch on Tall Fescue 
We could have an outbreak of brown patch on tall fescue in eastern Kansas in the next few days. Remember that this disease may continue to damage lawns to some extent throughout the summer. In most cases fungicides are not needed to control brown patch on home lawns; the turf will eventually recover. But if homeowners want blemish-free lawns, they can apply a fungicide. Homeowner-packaged products that are labeled for brown patch include thiophanate methyl (Fertilome Halt), propiconazole (Fertilome Liquid Systemic Fungicide) and triadimefon (Bayleton). All of these products work best if applied before symptoms develop. The fungicide chlorothalonil (Daconil) is no longer labeled for home lawn use. Several commercial fungicides (Heritage and Prostar) will give better and longer lasting (one month) control. Pythium blight. High night time temperatures have been favorable for Pythium blight development on a number of turfgrasses. If you have been over-watering tall fescue and notice softball-sized patches of mushy, rotted grass, it is probably Pythium blight. The best way to control this is to back off on the watering, especially during the evening hours. I have also seen a couple of cases of Pythium blight on creeping bentgrass putting greens. This is very unusual. In fact, I don't recall ever seeing Pythium blight on bentgrass mowed at putting height. Although this disease can cause significant damage, it doesn't seem to persist on the putting greens. Nevertheless, be on the lookout for Pythium blight.
Summer Patch 
Summer patch is widespread on Kentucky bluegrass this summer. Early wet weather in May and June followed by high temperatures were conducive for summer patch development. Look for small circular or frogeye patches developing in the lawn. Patch margins often have a bright yellow appearance. Summer patch is very difficult to suppress in home lawns after symptoms appear. (NT)
Contributors:
Ward Upham, Extension Associate; Ned Tisserat, Plant Pathologist; Chuck Marr, Vegetables
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