Weeds that appear in hot summer weather are some of the toughest to control. They germinate when your lawn is under stress from heat, humidity and drought and thrive under these conditions. Some summer weeds are grass like and are not susceptible to ‘normal’ weed control measures. Here are some of the weeds you will be seeing during these hot summer months.
If a bright, yellow-green, grass-like weed is detracting from your lawn’s beauty, there’s a good chance that you’re dealing with nutsedge. Nutsedge is a yellow-green warm season perennial. It has upright, grass-like leaves with a glossy upper surface and dull lower surface that emerge from the base of the plant. The leaves are 1/8 to 1/2 inch wide, up to 3 feet long, and have parallel veins with a prominent midvein. Its flat topped, burr-like flowers occur July to September and are affixed to the end of a stout triangular stem. It grows in all soil types, especially moist ones, but does not tolerate shade.
Nutsedge is a perennial weed that is hard to eliminate, mainly because it reproduces itself from tubers beneath the soil. If you hand-pull nutsedge, the tuber is usually left behind and will regerminate. Nutsedge grows quickly in low, wet soil. Left unchecked, it will grow as tall as 2-3 feet! Pro-Lawn-Plus’s 5 Treatment program includes a summer weed spray, that helps control nutsedge. But in lawns with an abundance of nutsedge, it is usually necessary to add one or two supplemental treatments.
Dallisgrass is a light green warm season perennial. It spreads upright forming clumps with leaves that are about 1/2 inch wide. It germinates in 60 to 65 degree soils, and although it thrives in the hot and humid south, it can be found all the way up to Maryland. The best way to remove this plant is by pulling out the clumps with your hands or a small garden tool since no herbicide is currently labeled to selectively control it.
Spotted Spurge is a summer annual that produces seeds in 60 to 90 degrees Fahrenheit. From a central taproot, it grows a flat, extensively-branched mat up to 2 feet in diameter. The stems leak a milky sap when broken. Its leaves are small, oval and up to 3/5 inch long. They can be purple spotted and hairy. Flowers occur June to October and are small and cup shaped. It is found in thin, drought-stressed soil in hot climates and closely mowed grass. This weed is resistant to many weed control products. To minimize Spotted Spurge, water deeply,, fertilize in autumn and avoid close mowing.
For information about these and other weeds, visit the Difficult to control weeds section of our website .
We are seeing high numbers of Japanese Beetle adults emerging now. They are flying around, feeding on trees, shrubs and certain perennials; mating then laying eggs in the lawn. Those eggs can turn into grubs if there is adequate soil moisture. In the summer of 2013, soil moisture is certainly abundant. So we expect a large grub population later this summer and into early fall.
The adult beetles can do a lot of damage in a short period of time. See this link fromfor control strategies. We do NOT recommend those yellow beetle traps because they tend to bring more beetles to your property. Insecticide sprays can help but generally rain will wash it off so in a year like 2013, multiple sprays would be necessary.
If you are on a lawn care program and you are not on the grub prevention option, you might want to consider it for 2013. The worst case scenario is that we have continue to have a wet July (so the grubs hatch and survive) then the turf dries out in August. At that time the turf has drought stress in combination with a reduced root system from the feeding of the grubs. That combination can cause damage that looks like this.Grubs in the soil.
To reiterate, if you have beetles you can expect to start seeing the grubs starting in late July and damage occurring from early August through early October. To prevent this type of damage to your property, we strongly recommend that you consider a grub preventive application as soon as possible.
Brown Patch disease (Rhizoctonia spp.) occurs in Maryland in warm, humid weather. The combination of daytime temperatures that are over 85°F and nighttime temperatures that stay above 65° F with little air flow leaving the grass moist for over eight hours are the perfect conditions for this turf disease. You can identify Brown Patch by its symptoms. Light tan lesions with dark brown edges across the middle or tips of the grass blades are signs you might have Brown Patch. On mornings with abundant dew, you will actually be able to see the signs of the fungal mycelium which look like cottony structures.
Click to enlarge
It is mainly a problem on improved varieties of Tall Fescue. If you have a variety that is especially susceptible to Brown Patch disease and the ideal environmental conditions are expected for an extended period of time, you might need to have your lawn treated with a fungicide to avoid having to. However, if a cold front is expected within a few days to lower the humidity and nighttime temperatures, it may not be necessary to spray.
If you suspect you have brown patch, avoid nighttime watering if you can. Afternoon and evening showers and thunderstorms on a humid night set up the ideal conditions for Brown Patch disease. More information on Brown Patch UMD
Please let us know if you have any questions about this disease.
Does your lawn have either of these things?
Whenever we have a period of rainfall, warm temperatures and high humidity, we always receive calls about mushrooms. We also receive calls about bluish-gray fungus on the lawn. The good news is that both of these are called saprophytic fungi, meaning they are not feeding on the grass itself. Therefore, neither lawn fungus needs to be treated with a lawn fungicide. Mushroom are the fruiting body of fungi that feed on rotting wood underground and they may be a symptom of a lawn disease called ‘Fairy Ring’; but it does NOT need to be treated. You can just kick the mushrooms over and they will dry out within a day or so. And with slime mold, you can either wash the particles (technically called pustules) off or kick it off of the grass blades it attaches itself to. Generally, when the lawns dry out and the humidity diminishes, the mushrooms and slime mold will disappear.
Here is the link to our website that describes mushrooms
Here is another link from Colorado State University that describes mushrooms in more detail
Finally, here is a link from Ohio State University that describes slime mold in more detail
Bugs seem to be on everyone’s minds lately. How many cicadas are coming? When will they get here? Will they ruin my trees or lawn? Wild estimates were tossed around to describe how many cicadas were expected to crawl out of the ground leading up to this year’s debut of a new generation of Brood II. Some said there would be up to 30 billion. Some said 1 trillion. Still others said cicadas would outnumber people 600 to 1. After reading this article from Freestate Nursery and Landscape News, it seems it really depends on where you are. And it looks like most of us in Maryland have nothing to worry about. I was looking forward to trying my first deep fried cicada this year too! Oh well, I know the regular Brood X cicadas will arrive in 2021.
Another bug people are talking about, not favorably, is the infamous stink bug. These annoying pests will not damage your lawn or ornamentals but can cause damage to vegetable gardens and fruit trees. Here is another great article in Freestate Nursery and Landscape News about stink bugs that you can read here.
Red thread disease and it’s associated lawn disease Pink Patch (Laetisaria spp) are both turf diseases that like cool, wet spring weather. It likes temperatures in the 60’s and low 70’s with high humidity and in soils with high moisture content. It is an interesting lawn disease because of the red fungal mycelium (strands) that are visible to the naked eye.
The disease develops in circular or irregular patches from 4 inches to 2 feet in diameter. Affected leaves within these patches are tan or bleached-white in color. From a distance, the patches usually have that reddish appearance, due to the presence of thick, red strands of fungal growth emanating from the affected leaves. It is through production of these “red threads” that the fungus spreads to healthy plants and survives unfavorable conditions. Small tufts of pink, fuzzy mycelium may also be present in or around the patches when the leaves are wet or humidity is high. After prolonged periods of disease development, the patches may merge to produce large irregularly shaped areas of damaged turf.
Red thread most commonly affects Kentucky bluegrass, perennial ryegrass, and sometimes tall fescue. Outbreaks usually occur in lower maintenance turf stands such as residential lawns, golf course roughs, and some low budget athletic fields. Red thread development is most common where turfgrass nutrition is poor but that is not always the case. Soils that have little or no topsoil and organic matter and don’t hold nutrients are susceptible to Red Thread and Pink Patch as well.
Generally, only in the worst cases of these two lawn diseases is it necessary to spray fungicides. There would need to be a prolonged period of cool weather to necessitate control products. A few hot, dry days usually will eliminate the symptoms.
Here is a fact sheet from the University of Maryland that explains the disease in more detail – http://hgic.umd.edu/content/documents/TT-24.pdf
Wild violet, is a cool season, perennial, broadleaf weed. It is one of the first plants to flower in spring, growing well during cool parts of the growing season, and is usually found in shaded, moist areas. The heart-shaped leaves have scalloped edges with a waxy coating.
The waxy coating on violet leaves tend to repel weed control materials, with little chemical being taken in by the plant. Violets tend to be resistant to most herbicides but are most susceptible in the spring while they are flower.
Controlling wild violets in a lawn or landscape can be a difficult challenge, and will certainly require more than one herbicide application before it is accomplished. As with any lawn weed, the best control practice is to promote a dense and healthy turf through soil testing to mointor pH, proper mowing, fertilizing and irrigation.
Creeping woodsorrel is a spreading perennial weed with a reddish-purple color that frequently roots at the nodes. The three heart-shaped leaves of creeping woodsorrel is nearly identical to yellow woodsorrel. Creeping woodsorrel is most commonly introduced to the landscape through nursery container-grown landscape plants. Once transplanted and established it will quickly escaped the landscape beds and invade the surrounding turf. Established creeping woodsorrel is difficult to manage and control because it is also resistant to most weed control products.
Japanese Stilt Grass, or Nepalese Browntop, is a pale green annual plant that grows up to 3 1/2 feet in height. The leaves are asymmetrical and lanced-shaped with a distinctive midrib and range from 1 to 3 inches long. Late summer yields flowers, and soon after fruits mature on the plant. It is found mostly in shady locations in moist or dry soil. It can be pulled from moist soil or mowed in late summer before the seeds are produced. The best way to control Japanese Stiltgrass is with very early spring pre-emergence herbicides. It can also be managed in the summer with certain post-emergence herbicides that are labeled for the control of summer annual grassy weeds.