A few weeks ago I was lucky enough to attend North Carolina State’s Tomato Field Day, at the Mountain Horticultural Crops Research and Extension Center in Mills River, NC. Every summer crowds flock from all over the Southeast to learn what’s new in the world of tomatoes. Since it’s not always convenient for you to drop what you’re doing to make a road trip to North Carolina, I’ll highlight something I learned from the field day.
Stink Bug Control by Dr. Jim Walgenbach
The brown marmorated stink bug (BMSB) was introduced into the United States from Asia. The insect pest was first found in Pennsylvania and is suspected to have made its way to the US in packing material. BMSB was first reported in 2009 in Hillsborough County, FL and since been found in additional Florida counties. It has a wide host range including fruits, vegetables, and ornamentals.
Fifth instar nymph of the brown marmorated stink bug on raspberry in Allentown, Pennsylvania. Photo Credit: Gary Bernon, USDA-APHIS
BMSB has a typical stink bug body shape and size with a mottled brown coloring. The key identification feature is alternating dark and light bands on the last two antennal segments.
Trissolcus japonicus adults. Female to the left; male to the right. Photo Credit: FDACS – DPI
Biological Control with Natural Enemies
Dr. Walgenbach’s team is currently researching the impact of suppressing BMSB populations by native predators such as: katydids; jumping spiders; earwigs; and lady beetles. Current observations indicate only a minor effect from these predators on BMSB.
BMSB egg masses parasitized by T. japonicus. Photo Credit: Matt Lollar, University of Florida/IFAS Extension.
Trissolcus japonicus Assessment
A regional effort has been implemented to monitor the introduction, spread, and efficacy of the Asian parasitoid Trissolcus japonicus. Trissolcus japonicus is a tiny wasp that parasitizes the eggs of various stink bug species. It was first collected from China and brought back to quarantine facilities in the US for evaluation, as a potential biological control agent. Host-specific tests have indicated that T. japonicus prefers to parasitize BMSB eggs over eggs of other stink bug species. It is suspected that release permits for the wasp will be available from the USDA in the near future.
Reporting in Florida
The brown marmorated stink bug overwinters in homes to keep warm. If stink bugs are found in yuor home, they may be the BMSB and should be reported to the Florida Department of Agriculture and Consumer Services Division of Plant Industry. Specimens should be collected for identification.
To follow the research of Dr. Walgenbach and his colleagues, please visit NC State’s Entomology webpage.
Cow birds feeding on beet armyworms. Photo: Josh Thompson
It’s that time of year when all kinds of insect pests are moving, especially caterpillars. Armyworms have been present but sporadic in hay fields, cotton and peanuts the past couple weeks across the Panhandle. Rome Ethridge, the Ag Agent in Seminole Co. Georgia, has reported seeing all kinds of different caterpillars this week. See his post on Seminole Crop E-News. Many times, cow birds are a dead give away of their presence, as shown in the picture above.
Seeing only a few caterpillars does not usually warrant an insecticide treatment for armyworms. This is because peanuts can withstand quite a bit of defoliation without it affecting yield. The treatment threshold for armyworms in peanuts is 3-4 caterpillars per foot of row before vines have lapped. After lapping, the threshold moves to 5 – 6 caterpillars per foot of row. For insecticide options, see Peanut Insect Control.
Beet armyworm in peanut. Photo: Josh Thompson
The good news is armyworms feed on palmer pigweed too; not enough to kill it though. Photo: Josh Thompson
Velvetbean caterpillar feeding on peanut foliage. Credit: Josh Thompson
Velvetbean caterpillars (Anticarsia gemmatalis) are an occasional late season pest which can have a big effect on a peanut crop. They can defoliate a field of peanuts in a matter of few days if left unchecked, making it important to monitor for this caterpillar.
Velvetbean caterpillars can range from green to dark gray and have distinctive stripes down the sides of their bodies. Sometimes they are misidentified as armyworms. A key characteristic is Velvetbean caterpillars wiggle wildly when handled. They are often seen in large numbers in peanut and soybean fields in late August and September.
The threshold for deciding to treat a field once the peanut vines have lapped is six larvae per foot of row. Even if a peanut field is only a week or two from digging, it may still be necessary to treat since Velvetbean caterpillars are known to feed on pegs after peanuts are dug.
For more information, see the Univeristy of Florida Velvetbean Caterpillar publication, and for insecticide recommendations see the UGA Peanut Insect Control Guide.
Former Jackson County Extension Director, Ed Jowers, identifying a Velvetbean caterpillar infestation in a peanut field.
Peanuts exhibiting hopper-burn symptoms. Credit: Josh Thompson
Earlier this week I visited a farm in Jackson County that had considerable damage from leafhopper insects, a condition usually called hopper-burn.
There several different species of leafhoppers that feed on peanut, one of the most common is the potato leafhopper (Empoasca fabae). See the picture below.
Potato Leafhopper. Credit: Steve Brown
The damage occasionally occurs in mid to late season peanuts when the plant-sucking insects move in from other hosts. Leafhoppers leave a distinctive yellow triangle-type pattern on the tips of peanut leaves. This is occurs after the leafhoppers suck the plant juices from the underside leaf mid-rib, causing the tips of the leaves to yellow.
Since the burned leaves are often not noticed until sometime after the damage has already been done, it is important to determine if insects are still in the area before making an insecticide application.
There are several effective chemicals to choose from for leaf hopper control. See the UGA Peanut Insect Control Guide for products and rates.
For more information on other insect pests, see Identification and Monitoring of Insect Pests in Peanut or contact you’re your local extension agent for assistance.