Fortunately, we are getting some moisture and relief from the drought conditions. The rain has been good for our fields, but also good for weeds. In some areas due to the drought, we have thin strands of perennial grasses; this has left lots of open ground and opportunities for both annual and perennial weeds. Three of the most problematic hard to control perennial summer weeds are: bull nettles, silver leaf nightshade, and Carolina horse nettle. All three of these are very difficult to control. However, your best chances for control are during the flowering stage which is right now. Flowering stage will typically start now and run for about the next month.
Both silver leaf nightshade and horse nettle are toxic to livestock. If you have cattle in pens or run short on grass, they can browse on these and the results can potentially result in death for your livestock. Due to these weeds’ ability to reproduce from both seed and rootstock, they are difficult to control. Shredding can help, but for lasting control you need to consider an herbicide. You will not eliminate all the weeds with a single spray but should hopefully expect about 70% control. In heavily infested areas, ground broadcast spraying will be needed. The most effective herbicides for controlling these three summer perennials are either Grazon P+D at 1 to 1.5 quarts per acre, GrazonNext at 1.5 to 2.1 pints/acre, Weedmaster or Range Star at 1 quart per acre, or Chaparral at 2.0 to 3.0 oz./acre. The total spray volume per acre should range between 10 to 30 gallons per acre. Due to the hairlike leaves, it is very important to use a good surfactant at 1 to 2 quarts per 100 gallons of spray mixture. Again, for optimal control, it is best to spray while the plants are flowering.
After a couple of bad grasshopper years, you would think we could get a break, but I have been seeing very large numbers of small grasshoppers in some fields this year. Typically, during a wet spring most of the young grasshopper nymphs (before they get wings) will die from all the rain. While we are wetter than we have been in a while, there are plenty of little grasshoppers that have survived the spring. In many areas I have seen grasshopper populations well above economic threshold levels, even though they are small, they will get large soon.
You can estimate the number of grasshoppers you have just by walking through your fields. Use the following levels to help make treatment decisions. At 3 to 7 hoppers per square yard you would have only light damage, at 8 to 14 you would reach the economic threating level where it should pay to take some preventive action and spray your grasshoppers.
There are many good products you can use to manage grasshopperstwo that have some good residual control include Dimilin and Vantacor, (previously known as Prevathon). Dimilin is an excellent product before the grasshoppers get wings, but we are getting close to the grasshoppers being too large for Dimilin to be effective. Vantacor provides excellent control and will work on the larger grasshoppers we have now; it will provide up to 6 weeks of residual control and cost around $13.00 an acre. Other good insecticides that provide immediate results, but do not have lots of residual control include any generic products containing lambda cyhalothrin, which cost approximately $3.40 per acre, and Mustang Max which cost around $4.75 an acre to treat. There are other pasture products available, but these tend to be the most cost effective. Check with one of our good local agriculture businesses and see what they are recommending.
For homeowners trying to control grasshoppers in their yards, landscapes, and gardens Cyfluthrin, bifenthrin, permethrin, cyhalothrin, and carbaryl are some of the active ingredients that control grasshoppers and that are formulated and packaged for homeowner use.
Look for one of these insecticides listed in the active ingredients on the product label. Read the label carefully to determine if the site you wish to treat (vegetable garden, fruit trees, etc.) is listed on the label as an approved site.