Dry Weather Stress

August 18, 2014 Leave a comment


By John Wilson

John Wilson

John Wilson

Our wet spring turned into a dry summer. At least we haven’t had extreme heat to make matters worse. Lawns, gardens and ornamentals are starting to show signs of our dry weather. Lawns starting to turn brown and wilting plants are the most visible signs. Low yields and poor quality vegetables are additional signs of heat stress.

Brown lawns are becoming a more common sight. Kentucky bluegrass has the ability to go dormant during summer to protect itself from heat and drought. This is what is happening when bluegrass lawns are turning brown… the grass is dormant, not dead.

To conserve water on turfgrass, it is fine to allow bluegrass lawns to go dormant. To keep them alive so they recover when cooler temperatures return, you should apply about a half inch of water every week or two, as needed, if you don’t get it from precipitation.

Fescue lawns are another story. You need to water them enough to keep them green… not golf course green… but at least a light green. Unlike bluegrass, fescue does not go dormant. If it turns brown, it enters a state which we call permanent dormancy… which is another way of saying it died and you will need to reseed the brown areas later this summer.

Ornamental plants and vegetables wilting during the heat of the day are also signs of plants protecting themselves from heat and drought. As long as the soil is moist and the plants only wilt during the day and then recover in the evenings, they are fine.

When plants wilt, you automatically assume they need water. In most cases they do, but check to see the soil is dry before watering. Larger leaved plants, like cucumbers, wilt during the heat of the day even when the soil is moist. This is the plant’s way of reducing the amount of water lost from leaves during the day. They do not need additional water… in fact too much water can injure them more than if you don’t water them at all.

Less obvious signs of heat and drought stress are bitter cucumbers, tomatoes with leathery brown bottoms, missing kernels in sweet corn ears, potato plants turning brown, poor fruit set, and the list could go on and on.

Most cucumber plants contain a bitter compound. When plants are stressed from heat, too little moisture, or poor fertility… bitterness in cucumbers is more prominent. Cucumber varieties listed as bitter-free or burpless are less likely to develop bitterness.

Bitterness is often limited to the stem end of the cucumber and the skin. Cutting off these portions will remove most of the bitterness. If the stress is severe, some cucumbers will be bitter all the way through and are best discarded. Even when pickled, they will remain bitter tasting.

When the bottom of a tomato fruit turns brown, this is blossom-end rot. It is caused by a lack of calcium in the fruit and peppers, squash and watermelon also can be affected. This deficiency is not due to a lack of calcium in the soil. It is result of factors that slow growth, such as heat or drought stress. To reduce blossom end rot, use mulch around plants, maintain uniform soil moisture and avoid overfertilizing with nitrogen.

If hot, dry conditions occur during pollination of sweet corn then pollination is often reduced. The results are sweet corn ears that do not develop kernels to the ear tip or have missing kernels throughout the ear. This sweet corn can still be eaten. Tomatoes with end rot can also be eaten if the brown portion is removed.

Some potatoes are turning brown due to hot air and soil temperatures. Once plants begin to die, harvest the potatoes. Even if there are not many potatoes or the tubers are small, once the plant dies tubers stop developing. If left in the ground, they are likely to rot.

For more information on watering your lawn or garden, contact your local UNL Extension office.

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Wimpy Wasps

July 26, 2014 Leave a comment


By John Wilson

Extension Educator

I recently made a stop at a business in town and was surprised to see seven large wasps hovering around the edge of the sidewalk. They looked quite intimidating and I noticed several people give them a lot of room as they walked by. Actually that wasn’t necessary because these large wasps are our perennial mid-summer visitor, the cicada killer.

Each year, people will bring large wasps in a variety of containers to the Extension office while the less daring just describe what they see around their homes. The description usually goes something like this… “It’s a large yellow and black wasp that kept buzzing around the same place in the lawn.” or “It’s a huge hornet that keeps coming back and won’t go away.” or my favorite, “It’s the biggest wasp I’ve ever seen and it scares the bejeebers out of me.”

These are all fairly accurate descriptions of the cicada killer. These large black and yellow wasps, up to two inch long, tunnel in disturbed areas, creating soil mounds and cause concern about stings. In spite of their menacing appearance and seemingly aggressive behavior, these wasps only rarely, if ever, sting. As one insect expert described them, they are a wimp in the wasp world. They are not a threat unless stepped on with bare feet or a person tries to hold one in their hands.

These wasps dig a tunnel in the soil about a half inch in diameter. They get their name, cicada killers, by the next step in their life cycle. After digging a tunnel, they find a cicada and sting it which paralyzes the cicada, but does not kill it. Then they drag this cicada into their tunnel and lay an egg on it. When the egg hatches, the cicada provides food for the larva. It will eventually form a pupa and then the adult wasp hatches out next summer.

These soil-nesting insects hone in on what are, to them, major landmarks… a stick or a small stone… and use these to locate their nest. When someone moves into the area, suddenly the landmarks seem different, so the wasps dart around, reassessing their position. The wasps are not aggressive, but it looks that way. In spite of their intimidating appearance, these wasps can and should be ignored.

Although the cicada killers are not a problem, there are other insects that do deserve our attention. These include crickets, boxelder bugs, Asian lady beetles and other insects that intentionally or accidentally get into our homes. I’m just starting to see crickets now and the others will be looking for shelter later this summer. This is a good time to spray around the foundation to form a barrier to control them before they get into your home and also to seal up any cracks or crevices where they might actually get it. A little prevention now will go a long way to preventing problems later.

For more information about insects that might be invading your home, contact your local UNL Extension office.

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Eliminating Mosquitos

June 12, 2014 Leave a comment


John Wilson

John Wilson

Nothing spoils working in your garden or an enjoyable evening in the backyard quicker than being swarmed by mosquitos. The recent rains have provided relief for farmers and homeowners, but they also cause problems for anyone working outside. Rain creates ideal sites with standing water for mosquitoes to develop.

To reduce this problem, eliminate mosquito breeding areas that catch and hold water. Check for leaf-clogged gutters, puddles, bird baths, old tires, cans, bottles, lagoons, and children’s wading pools. Drain water from these when practical. Rinse out your bird bath weekly.

Still water in birdbaths, ponds or lagoons may also be treated with Bacillus thuringiensis, or Bt, in the form of biscuits, available at some garden and hardware stores. The sustained release of the active ingredients of these products may provide up to 30 days control of mosquito larvae. These products specifically attack mosquito larvae and will not harm fish or birds or wildlife that drink the water.

Only female mosquitoes possess piercing-sucking mouthparts and require a blood meal to produce viable eggs. Eggs are laid in batches between blood meals. A single female may deposit several hundred eggs in her lifetime. Under favorable conditions, a new generation of mosquitoes can be completed in less than a week.

To keep mosquitoes out of your home, check all doors, windows and window screens, to make sure these are tight and in good repair. Screens should be 1/16th-inch mesh or smaller to prevent mosquito entry into the home. Keep porch lights off as much as possible in the evening. Or, replace traditional white light bulbs with yellow ones to help reduce the attractiveness of your home to mosquitoes and other night-flying insects.

To prevent mosquito bites when working outside, wear long-sleeved shirts and full length pants. Two layers of clothing are more difficult to penetrate by biting mosquitoes. Wearing light-colored clothes will reduce also your attractiveness. Work outdoors when it is cooler, or when there is a brisk air movement or strong sunlight. Different species of mosquitoes have specific feeding periods, but many are most active in the early evening hours, generally from 5 to 9 p.m.

But, because female mosquitoes are attracted to the carbon dioxide that we exhale, using an insect repellent while outdoors may be the most important method to prevent mosquito bites. You can use repellents containing DEET. These come under numerous brand labels and many formulations such as lotions, gels, aerosols, creams, and sticks.

Mosquitoes are always a nuisance, but they can also pose a health risk because of their potential to transmit West Nile Virus (WNV). In humans, WNV causes flu-like symptoms such as fever and muscle weakness. WNV can also cause encephalitis (an inflammation of the brain), disorientation, convulsions and paralysis. People over 50 and those with weak immune systems are especially vulnerable to the disease and should take extra precautions to avoid mosquito bites.

The Elkhorn Logan Valley Public Health Department will be working with the Nebraska Department of Health and Human Services West Nile Virus Surveillance Program this summer to monitor for West Nile virus. West Nile is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird and in turn the mosquito can transmit the virus to humans.

This year, testing will only be done on corvid species of birds (blue jays or crows in our area). If you find a dead bird, and it is in good condition and has been dead less than 24 hours, please double bag the bird in sealable plastic bags, freeze it, and immediately contact the Elkhorn Logan Valley Public Health Department at 877-379-4400. Testing will only be conducted on birds that are in good condition with no evidence of maggots or rotting.

The goal of the surveillance program is to collect dead birds for submission to a laboratory for testing. Finding the virus in birds provides an indicator to public health officials of the level of the virus in the area and the risk to human beings of contracting the disease.

For more information on mosquito control, or on the WNV Surveillance Program, contact your local UNL Extension office.

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The Great Tomato Challenge

June 7, 2014 Leave a comment


John Wilson

John Wilson

Over the years, I’ve observed an informal competition between gardeners to see who can produce the first ripe tomato. I’ve actually had people stop me in the post office or grocery store to tell me how close they were to having that first tomato… or first BLT sandwich! Their “green thumb” efforts are being challenged again this year by Mother Nature.

We’ve had a lot of rain and driving winds, perfect conditions for early blight to develop. Early blight usually starts on the lowest leaves and gradually moves up the plant. Once a leaf is infected, you cannot cure it, but you can prevent it from spreading to other parts of the plant with a fungicide labeled for use in the garden. You will need to repeat these applications every 10 to 14 days… or more frequently if it rains… to protect the new growth. Always observe the waiting period between a fungicide application and when you can safely harvest and eat your tomatoes.

Other things you can do to help prevent the disease this summer is to mulch your tomatoes if you haven’t done so already. In addition to helping keep a more constant moisture level in the soil and preventing the soil from getting too hot around the roots which injures them, mulching also reduces the likelihood of soil particles containing this disease from splashing onto the leaves.

That leads to the second thing you can do to help prevent this disease… always water tomatoes at the base of the plant, not with a sprinkler. A sprinkler, or rain, splashes soil on the plant… and they also keep the foliage wet. The disease needs moisture on the leaf surface for the spore to germinate and infect the leaf. You can’t control the rain, but don’t add to the problem with overhead irrigation.

Staking or caging tomatoes will help reduce the severity of this disease because it keeps the plants upright and promotes better air circulation which causes the foliage to dry faster which reduces the possibility of infection occurring. It also prevents the fruit from coming in contact with the soil which may lead to blemishes or decay… and it makes harvest much easier.

To prevent this disease in future years, clean up all plant debris from tomatoes, potatoes, peppers and eggplant this fall and remove it… because the same disease can infect all four of these plants. Don’t put this plant material in your compost pile or till it into the soil. The disease overwinters on plant debris and could infect these plants next year. Also rotate where you plant these in your garden so you don’t plant any of them in an area next year where any were planted this year.

One other thing that occasionally foils competitors in the great tomato challenge is when they fertilize their plants, particularly with a nitrogen fertilizer. It’s almost amusing (to me, not to them) when someone calls in and asks why their dark green, healthy looking, six foot tall tomato plants are not putting on any tomatoes. These calls usually come with a statement like, “These are the best looking tomato plants I’ve ever grown… and they aren’t setting any tomatoes!”

Tomatoes like nitrogen fertilizer and applying it early will promote these monster plants… BUT… nitrogen fertilizer also keeps plants in a vegetative state (growing leaves and stems) rather than letting them transition to a reproductive state (setting on fruit). Delay fertilizing your tomatoes until they have already set on a couple tomatoes that are the size of a marble. Then fertilize in moderation because overfertilizing is one of several factors that contributes to blossom end rot. We’ll talk more about blossom end rot another day as tomato harvest draws nearer.

For more information on disease control in tomatoes, or other vegetables in your garden, contact your local UNL Extension office.

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Did Your Lawn Survive Winter?

March 24, 2014 Leave a comment


By John Wilson

Extension Educator

With one cold blast after another and very little snow cover, many homeowners are questioning if their lawns survived the winter. We will have a better idea on the extent of winterkill as lawns start to green up with warming temperatures in the next week or two.
Green color at the base of old leaves may or may not be this year’s growth. It could be left from last year and may not be a good indication of plant survival. However, ½” or more of green leaf material on turf plants in our lawns is a pretty good indication that the leaf is alive and growing.
A natural response for many homeowners is to mow as soon as possible to remove that brown leaf material to speed the overall appearance of green-up. This dead leaf material is natural protection and insulation from potential Alberta Clipper cold fronts that still may blow through. This could be especially damaging to turf areas that are already weakened by winter. Therefore, our advice is to hold off mowing for another week or two to lessen the chances of damage from cold snaps.
Another consideration this year is when and where to apply preemergence crabgrass preventors. We normally recommend late April or early May for a first application followed by a second application in late June. That is even more important than ever this year. I know some people like to get out and make that first application in early April, or even as early as late March.

John Wilson

John Wilson

The reason it will be especially important to NOT do that this year is we don’t know yet if there are areas of the lawn that will need to be overseeded or completely reseeded. The products normally used for crabgrass control will also control or kill newly seeded turf grass seed. So wait to apply preemergence products until you know if you will need to overseed or reseed.
There is an option for crabgrass control in new seedings or areas that were overseeded. There is a product called Tupersan, which has the active ingredient siduron, that will control crabgrass but not injure new seedings of bluegrass or fescue. The two drawbacks to this product is it is not readily available, you will probably have to go to a garden center to find it, and it is more expensive. However, it is your only choice on new seedings to control the early germinating crabgrass.
Your other option is to wait until any new grass seedings have emerged and then apply the more commonly available products in mid- to late June. Once new seedings have emerged, the preemergence products will not affect the stand. The problem is, it will not control any crabgrass that has already emerged either.
One final consideration is whether to water your lawn now. Many areas have received light rains or snow, but this has been quite variable. Check the moisture in the top 6-8 inches of soil. If it is dry, consider watering on a warm day. Do this in the morning so it has time to soak into the soil… and only put on enough water so it doesn’t pool on the soil surface. Too much water that doesn’t soak in will form a layer of ice around the grass crowns and could further damage the turf.
For more information on assessing winterkill and repair of winter damaged lawns, check out the University of Nebraska turf website at http://turf.unl.edu or contact your local UNL Extension office.

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