Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
August 26, 2008
It may seem an odd time of year to be reading about rust on turfgrasses, but Logan County has had an outbreak this past two weeks. Turf rusts generally appear in cooler temperatures and we recently experienced a week of cool days with low humidity and very cool nights. The result was a nice crop of rust in the lawn.
All turfgrasses can be infected with rust fungi, but Kentucky bluegrass, perennial ryegrass, tall fescue, and zoysiagrass tend to be most susceptible. Early symptoms of rust diseases include light yellow flecks on leaves and stems, giving the lawn a yellow cast. The leaf tissue ruptures at these yellow spots, and spores of the fungus are produced. The pustules may be yellow, orange, brown, or red. The spores rub off very easily on hands, shoes, clothing, and animals. Often, the disease goes unnoticed until you mow the lawn and see that your white shoes are covered with a dusty coating of rust-colored spores.
Severely infected turf appears thin and tinted yellow, red, or brown, depending on the fungus and time of year. The turf becomes weakened, unsightly, and more susceptible to injury from environmental stress and other disease pathogens. Grasses growing slowly under stressful environmental conditions (such as big swings in temperature and moisture) are most susceptible to rust, particularly when water, fertility, and soil compaction are inadequate for good growth. There are also varieties with resistance and susceptibility to rust.
Management measures should target stress areas. Leaf wetness is required for infection, so it is important to water early in the day so the turf can dry before night. Water turf infrequently, but to a depth of 6 inches or more at each watering. Avoid frequent, light sprinklings. Fertilize to keep the grass growing about 1 inch per week in summer and early fall droughts. Use balanced fertilizer and do not apply excessive nitrogen. As the grass grows, it pushes rust-infected leaves outward, making it easy to mow and remove infected blades. It may be helpful to catch these clippings and remove them from the area. Mow regularly to remove infected leaf tips, but avoid mowing below the recommended height for the particular turf species. Prune surrounding trees and shrubs to improve light penetration and air circulation around densely shaded areas.If the lawn is badly infected or the combination of rust and other stress produces a poor lawn and forces a renovation, it is ideally done in late August or early September. Use a blend of turf cultivars with resistance to rust, but beware that what was once resistant may no longer be. The rust fungi keep evolving and eventually defeat the old-line resistance. Preventive fungicides are available, but they offer only a temporary solution. The fungicide treatments tend to be costly and time consuming. Daconil is the most common fungicide used on turf, but following the management practices will produce better long-term results. To offer a ray of hope, diseases must have ideal conditions to develop. Just wait for a major weather change and the rust will go away. At least for a while.
August 18, 2008
We have discussed the timing of grub control treatments in past columns. As a reminder, the date would have been early August for annual white grubs. We are now approaching treatment for grubs coming from the Japanese beetles. Knowing when to treat grubs is one thing, and knowing what product to use is another.
Many grub control treatments are combined with fertilizer products, and this is the appropriate time to apply a fall fertilizer treatment. It seems each year provides more "stand alone" treatment options as well. Diazinon used to be the product of choice for many homeowners, but the cancellation of home horticulture uses of the product created confusion in selecting a product. The other wild card was the use of diazinon helped eliminate mole problems (by driving them to the neighbor's yard) since the product killed grubs and reduced earthworm populations. Many of the products currently used do not affect earthworm populations, and on the whole that is a good thing since earthworms greatly benefit lawns. There are now some "soft baits" available for mole control that are effective.
Current recommended products include halofenozide (Mach 2), Heterorhabditis bacteriophora (Cruiser), imidacloprid (Merit), and trichlorfon (Dylox). Many of the chemicals have other brand names in addition to the ones listed in parenthesis. It is also recommended to drench treated areas with a half inch of water within 30 minutes of application, and this is especially important with liquid applications. Application just ahead of a rain is usually best. Granular applications buy a few days of time, but still need to be watered into the root zone where grubs are active. The products with Merit will take three weeks or so to activate. Some reputable sources also list carbaryl (Sevin) granules as an option for grubs from green June bugs and Japanese beetles. Carbaryl does reduce earthworm populations to some degree.
In good growing seasons, it normally takes at least 10 grubs per square foot of lawn area to justify treatment. In less favorable seasons, this number can be reduced to six to eight grubs per square foot. As your gasoline bill for the lawn mower can attest, this has been a good growing season to date.
Consider many factors when selecting a product. These would include combination with fertilizer, effectiveness, species controlled, cost, and the effect on the environment. The Cruiser product is actually a nematode, and would be the most environmentally safe. It also costs about $55 to treat about 3000 square foot of lawn. The other organic product sometimes mentioned for control of the Japanese beetle grubs is milky spore. This product is a bacteria which takes several years to become very effective and can cost around $35 for 2500 square foot of lawn. You can't apply any other controls with milky spore since you need high populations of grubs to increase the bacteria populations to high levels and provide transmission between grubs.
Good luck as you decide your attack plans against grubs. The choices are many, and the attainment of the "perfect" lawn is a goal many strive for. Remember, you can live with some grubs. However, too many can be devastating to a lawn. With Japanese beetle populations at very high levels in many areas, odds are great there will be grubs to battle.
August 14, 2008
If you have been following a foundation spray program all year, keep it up. If you haven't been, it is probably time to start. The foundation spray program is your first line of defense against nuisance pests in the house. It cuts down on crickets, millipedes, spiders, ants, and many others that find their way inside.
To accomplish a foundation spray, you would select a material such as permethrin or bifenthrin to begin with. Then spray the foundation and the adjacent foot or two of soil or plant material with the spray mixture. Both these products are cleared on most types of plants. Foundation treatments should be applied every 7-15 days depending on the temperatures. The materials break down quicker in hot weather.
Foundation treatments won't prevent everything from getting in the house, and they certainly won't kill things already in the house. For insects already in the house, you have a few options. The first is mechanical control. This is fancy language for something like a flyswatter, shoe, vacuum cleaner, flypaper, or glue boards. The next is chemical control. This basically means aerosol cans inside the house. The most common ones are for flying insects or ants, although many of the flying insect killers now have permethrin in them and can last quite a while.
August 14, 2008
It has been a banner year for diseases in many plants. The lawns are starting to show some of the diseases as well. Conditions have been ideal for many of the fungi that cause up problems. Humidity makes an ideal environment for many diseases, but there are some that like drier conditions. Dollar spot, brown spot, and rust have been noted in area lawns.
There are treatments available for diseases in home lawns, but they can be rather expensive and time consuming. Treatments would be applied on a 7-14 day basis throughout the season. It isn't recommended for homeowners to treat diseases in the lawn. The recommendation is let nature take its course, and then do some reseeding if needed.The disease needs a susceptible host, the right environment, and time to cause us problems. If you do some reseeding, use a newer variety with good disease resistance. This attacks the susceptible host part. Also, keep your turf growing well to prevent weakened grass plants from being more susceptible. The diseases will only be present during certain weather, and as the weather changes the diseases will go away.
August 14, 2008
We are still experiencing a large number of beetles in the garden. This includes not only the Japanese beetles, but also the recently emerged Western corn rootworm beetles. These small black and yellow striped beetles are of concern around cucumbers, melons, and pumpkins since they can carry a wilt virus.
It is a good idea to treat your vining crops with Sevin, permethrin, or bifenthrin on a weekly basis. It is important concentrate on the new runners to help prevent damage from squash vine borers.The numbers of Japanese beetles seem to be declining somewhat. Of course there are still plenty in many areas, but the population should continue to decline until the last of them are finished off by frost. As favored food sources are consumed, less likely plants may be attacked. This may mean a recheck of things around the landscape. I've recently seen them on marigolds, and seen some limited feeding on red maples. These plants are in the less preferred categories.
August 6, 2008
The time of year has arrived to put that final push on to prepare your lawn for the upcoming winter months. What you do now will have a big impact on how your lawn will look next spring. The timing of many of the treatments will begin in about a week, so now you'll have plenty of time to make your list and complete your shopping.
Keep mowing when the grass or weeds dictate mowing. The rule of thumb is to remove no more than a third of the leaf blade at any one time. This means that if your desired mowing height is 2 inches, you should be mowing when the grass gets 3 inches tall. No summer slump this year, due to all the rain. It figures that we mow every three days all summer long when gas is hovering around the $4 mark.
I have had some grub samples brought into the office this week. This means that the grubs are active. Grub problems are normally found first along walks, driveways, or patios. The insecticide must get to where the grubs are, so make sure to water the liquid formulations in as soon as they are applied. The two widely available products are GrubX (halofenozide) and Merit (imidacloprid). Remember the active grubs now are from the June bug, and we'll want to wait another two to three weeks on trying to apply grub treatments for the Japanese beetle grub. Carbaryl (Sevin) granules are an option for Japanese beetle grubs, but don't work on the other species.
Yellow grass tops are visible in many areas. This tends to happen in very wet years when nitrogen is taken from the root area, and trees and shrubs grab available nutrients. In the past, treatments haven't had much effect in the current growing season. Next year you won't see the same problem.
Fall seeding of grass should be done between August 15 and September 10. This is a tried and true date, but the end of the world won't come about if you are a week later. The goal is to give the seed enough time to germinate and become established before bad weather arrives. Seed at the rate of 4 pounds of seed per 1000 square feet on bare spots, or half that rate on overseedings.
If you have a compacted yard, or have a deep thatch layer, these seeding dates also define ideal times to dethatch or aerate. Thatch layers should not be over 1/2 inch deep for optimum growing conditions. When aerating, make sure you use a core type aerator.
Fall fertilization is also a good practice. If you haven't fertilized in the last month, consider applying a fertilizer treatment around September 1. Use about 8 pounds of 13‑13‑13 fertilizer per
1000 square feet of lawn. Try to avoid the high nitrogen fertilizers this late in the year. It's hard enough to keep up with the mowing as it is, and nitrogen promotes top growth. The even analysis fertilizers will also promote root growth, which is what we want going into the late fall and winter.
Crabgrass and other annuals grass weeds can be seen about everywhere. They will die with the first frost, so treatment is not available or recommended in the fall. Make a note of where these grasses are, and an overseeding to thicken up the grasses you want there may help crowd out the annuals. Preventative treatments may also be applied in the spring (around April 1 depending on soil temperatures) to kill the germinating seeds.
Last, but not least, is broadleaf weed control. Fall is a particularly good time to treat problem perennial weeds since they are sending food down to the roots to overwinter. A spray
about the 3rd or 4th week of September (making sure to use the appropriate product) can do a world of good on the perennial weeds. Remember to be very careful with herbicides around perennial plants since they are also getting ready to overwinter. Also, waiting this late in the season reduces drift potential for the neighbor's garden. Dicamba is particularly prone to vapor drifting, for up to two weeks, with hot, sunny conditions. It's hard to get a good weather forecast for two weeks, let alone the week we are in.
August 1, 2008
With the predominant grub rapidly switching to the larval stage of the Japanese beetle, it's best to hold off grub treatments for at least a couple of weeks. The idea is to get all the eggs hatched before your application.
The eggs of the Japanese beetle and green June bug usually aren't hatched until three or four weeks after the June bug eggs. This would push treatment time to the end of August, rather than the beginning. More on grub treatment will follow in a few weeks.
August 1, 2008
This is Logan County Fair week. We'll be hard to reach because of the various 4-H Shows. If you really need to speak with someone in the office, you may always call the office at 732-8289. You may have to leave a message on the answering machine, but we'll get back to you as we are able.
August 1, 2008
With the numbers of aphids increasing in gardens, on trees, and in fields, that brings us to a couple of predators that we are familiar with. One is the Asian lady beetle, and the other is the syrphid fly. Both of these increase populations greatly when their food source, in this case aphids, increases.
We are all familiar with the Asian lady beetle. It is actually a beneficial insect since it eats aphids. It is also a nuisance pest when it gets all over the side of your house, or flies around your light over the kitchen table. The vacuum cleaner is the best control in the house, and think twice about treating them outside since they are helping you keep from having black, sticky lawn furniture.
Syrphid fly is a generic name given to an entire group of flies. There are some differences in appearance and color, but the yellow and black color is the major one in our area. The other names for syrphid flies are hover flies or flower flies. They tend to hover around your arms and face when you have been perspiring, and land to lap up the sweat. They are also commonly found on flowers, hence the flower fly name, and do a good job of pollinating.
Syrphid flies are actually beneficial insects. They help pollinate, larvae feed on dead organic matter, and the larvae are predators of aphids. They cannot sting, but their mouthparts can usually be felt when lapping up sweat from sensitive areas. You may feel a slight pinch.
August 1, 2008
People are beginning to complain about leaking sap coming from trees. Actually this has been going on for a week or so. What happens is a fine mist of sap coats things beneath a tree. This is actually called "honeydew," which is a secretion of sucking insects such as aphids. What makes matters worse is a fungus begins growing in the honeydew, making it turn black.
There are two ways to deal with the problem. The first way is to spray the entire tree with a product, such as malathion, to kill the insects. The second way is to move anything portable from under the tree. If you opt for the first option, you need to make sure you can spray the entire tree. The kind of weather predicted will increase aphid numbers at a very great rate.
The end effect on the tree isn't all that great as long as adequate moisture is available. This means a shot of water when it stays dry for a week or more. We'll also be coming up on lawn fertilization time in about a month, so that fertilizer will help the trees as well.