Agricultural Updates

Alfalfa Webworms

Many growers have noticed damage in their alfalfa fields lately, with leaves being eaten and webs in the top several inches of the plant. These signs likely mean that alfalfa webworms are present in your fields.

Alfalfa webworms are a small, green caterpillar that can infest alfalfa as well as soybeans. As they grow, alfalfa webworm larvae turn dark green and reach 1 to 1 ¼’’ long. They have stripes extending down the length of their back, with three dark spots on each side of their body on each segment. Webworms generally feed in the upper canopy of the plant by encasing the top leaves in a webbing and consuming the leaves within the webbing. As they grow larger, they may feed outside the webbing as well. Telltale signs of an alfalfa webworm infestation are defoliation of the upper leaves and webbing in the upper canopy filled with black specks of fecal matter. Alfalfa webworm infestations can lower the hay quality with webbing and fecal matter while severe infestations can even reduce alfalfa stands.

The easiest way to control alfalfa webworm is to harvest the alfalfa. The University of Missouri does not have specific threshold data, but Texas A&M University entomologists recommend treatment if 25 to 30 percent of plant terminals are infested and harvest is greater than two weeks away. Otherwise, an early harvest will remove the webworms habitat and control the infestation. Several insecticides are labeled to control alfalfa webworms, but harvest restrictions can vary from 0 to 15 days after an insecticide application. Be sure to read and understand the label before applying an insecticide.

Another pest that may show up in our alfalfa fields is the fall armyworm. This insect migrates northward every year from the Gulf C oast, and its larvae will feed on alfalfa, pastures and late-planted corn. Fall armyworm are gray or brown with black bumps on their body and have a distinctive white “Y” mark on their head. The fall armyworm will chew on the tender leaves of plants, causing “window-pane” like damage in corn that can progress to large holes in the upper leaves. On forages, the damage appears as large brown spots in the field that appear to have died due to drought. This is actually the result of the plants dying due to a lack of water movement, although it is rare for armyworms to kill healthy, established plants. Scout for fall armyworm early in the morning or late at night, as they are inactive during the day. For economic thresholds on fall armyworm damage, contact your local University of Missouri Extension office.

For more information or if you have questions, please contact me at the Harrison County Extension Office, (660) 425-6434 or email me at LukeA@missouri.edu.
(Written 8/9/19)

Orange Gall Midge

Reports from Nebraska, Minnesota and Iowa indicate that orange gall midge are showing up in soybean fields in these states. This pest has never been reported in the state, but its close proximity across state lines mean it is likely present in fields in Missouri.

Orange Gall Midge, sometimes referred to as soybean gall midge, is a relatively new pest, first being found in Nebraska in 2011, with first damage reported in South Dakota in 2015. Appearing originally as small, white larvae, the gall midge turns bright red or orange as it matures. The larvae feed inside the stem of soybeans, causing swelling and abnormal growth near the soil surface. The soybean plant will have dark brown markings on its stem, resembling some stem diseases. It will then snap off easily near the ground, revealing the white or orange midge larvae. Most gall midge damage is noticed in soybean plants that are showing symptoms of damage or disease, with injury generally more severe along field edges. Because it is usually found in damaged fields, it is not known whether the orange gall midge causes significant damage or whether it is a secondary pest. Treatment with insecticides is not recommended because control is unlikely for the larvae that are protected while feeding inside the stem.

To scout for orange gall midge in your soybeans, look for field edges with wilting or dying soybean plants. It’s likely that the midges will appear in fields that were in or border fields planted to soybeans last year. Check to see if the stems of the damaged plants appear brittle or have dark discolorations near the ground. If so, snap off the plant near the soil surface and you should be able to see the white or orange maggots feeding inside the darkened portions of the stem. Very little is known about this pests biology, and even less is known about control measures. If you suspect orange gall midge is present in your soybean field, please contact your local University of Missouri Extension office. You can reach me, Andy Luke at (660) 425-6434 or LukeA@missouri.edu.

Japanese Beetles 2019

Reports from counties in Central and southern Missouri indicate that Japanese beetles are emerging and that high populations of the pest can be expected this year. While numbers of beetles may currently be low in the area, it is only a matter of time before they start to show up in our fields, yards and gardens.

Japanese beetles are a metallic green beetle with bronze-colored wing covers often found in crop fields. Approximately one third to one half inch in length, they will have 5 tufts of white hair on each side of the abdomen. Having a wide range of host plants, they will feed on over 300 different species of vegetation, with roses and soybeans seeming to be particularly desirable. The beetles will feed on nearly all plant parts and are most active on warm, sunny days. In many plants, they prefer to feed on the upper leaf surface between leaf veins, which results in skeletonization of the leaf. Japanese beetles are able to overwinter in Missouri as grubs and emerge from the soil from June to August. While the grubs can damage crop plant roots, thresholds for insecticide applications are based on feeding damage by adults.

Economic thresholds for Japanese beetle control vary by the infested crop. For corn, treatment is recommended if three or more beetles are present per ear or if silks are clipped to one half of an inch in length. Do not apply insecticide if pollination is more than 50 percent complete. Leaf feeding in corn does not generally impact yield, so insecticide applications should not be made until silks are present. In soybeans, treatment is recommended based on the percent defoliation, not on the number of beetles present. If soybeans are in the vegetative stage, the threshold for treatment is 30 percent defoliation. Once they begin flowering, the threshold drops to 20 percent defoliation. Forage crops such as alfalfa and fescue do not have established economic thresholds, as treatment is rarely warranted in these species.

Japanese beetles produce aggregation pheromones, so they have clumped distributions in fields. Border sprays can be an effective management option if the population is restricted to the field edge, while also reducing non-target effects of insecticides on pollinators and other beneficial insects in the field. Some growers and homeowners like to purchase Japanese beetle traps for their land, but they must use caution when doing so. The pheromone in the trap will attract high numbers of beetles to the area where they will feed on vegetation throughout the summer. The beetles will also lay eggs and over winter near the trap site, which can lead to greater damage in future years.

Coping with Disaster

The following link to MissouriFamilies.org has a lot of information about
helping people in financial crisis and emotional distress.

2016 Custom Rates for Farm Services in Missouri

The rates reported in this guide are based on a statewide survey conducted by mail in the winter of 2017. Farmers, agribusiness firms, aerial applicators and land improvement contractors responded to questions on the rates they were charging or paying in 2016 for custom services, excluding the cost of materials being applied.

2016 Custom Rates for Farm Services in Missouri G302.

Private Pesticide Applicators Training

Individuals needing to obtain or renew their Private Pesticide Applicator certification for the purchase of restricted use pesticides may come into the Harrison County University of Missouri Extension office and watch a 2 1/2 hour training video. The training is free, except for $12 for the Private Pesticide Applicator Reference Manual, if you already have the manual, then you must  bring it to the training. Family members can share one manual. Private Pesticide Applicator certification is valid for 5 years. To schedule a time to view the video contact the office at 660-425-6434 or harrisonco@missouri.edu.

Ag business

MU Extension publication G810, Missouri Fencing and Boundary Laws
MU Extension publication G427, 2018 Cash Rental Rates 
MU Extension publication G302, 2016 Custom Rates for Farm Services