Protect soybeans from stink bugs
Kelley Tilmon, OSU Extension field crops entomologist, reminds soybean growers to scout for stink bugs in soybeans and provides the following information and recommendations:
As our beans start to put on pods, it’s time to start scouting for stink bugs. Prevent seed damage by scouting and applying rescue treatment at appropriate threshold levels.
Several species of stink bugs are found in soybeans. These include the green, the brown, the red shouldered and the brown marmorated stink bug. Both nymphs (immatures) and adults feed on the developing seed by using their piercing/sucking mouthparts to poke through the pod. Seed fed upon by a stink bug will have a flat or shriveled appearance within the pod. Another stink bug found in soybean fields, the spined soldier bug, is actually a beneficial insect. The spined soldier bug looks similar to the brown stink bug, but has sharper points on its shoulders, and is browner on the underside (the brown stink bug is actually more green underneath).
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Generally, the damage caused by stink bug feeding is not seen until harvest time, because the pod usually retains its shape, despite the smaller seed. Therefore, it is important to scout early and control if necessary. Most insecticides labeled for soybean include stink bugs on the label, and most are adequately effective. Keep in mind it is easier to kill immatures than adults.
To sample for stink bugs, take multiple 10-sweep samples with a sweep net in multiple locations throughout the field. Often stink bugs start on field edges, particularly if there are woodland field borders. Concentrate sampling in those areas first. Average the number of stink bugs in the 10-sweep samples.
The threshold to treat is four or more stink bugs (adults and nymphs combined). If soybeans are being grown for seed, the threshold can be dropped to two or more stink bugs.
August perennial forage establishment
A 2017 article from Rory Lewandowski reminds us that August provides growers with another window of opportunity to establish a perennial forage stand.
According to the 15th edition of the Ohio Agronomy guide, planting of alfalfa and other legumes should be completed by mid-August in Northern Ohio and by the end of August in Southern Ohio. These timelines take into consideration average frost dates and the time needed for forage plants to develop a root system capable of overwintering.
For example, at about eight to 10 weeks after emergence alfalfa plants pull the growing point below the soil surface, a process termed "contractile growth." The alfalfa plant needs to reach this growth stage to overwinter. Clover plants also need to have a crown formed, and grasses should be at least in the tillering stage of development before the onset of winter.
Sclerotinia crown and stem rot is a concern with no-till seedings of alfalfa in late summer and especially where clover has been present in the past. This pathogen causes white mold on alfalfa seedlings. They become infected during cooler rainy spells in late October and November, the disease develops during the winter, and seedlings literally "melt away" in winter and early spring.
It can be devastating where the pathogen is present. No-till is especially risky where clover has been present because the sclerotia germinate from a shallow depth. Early August plantings dramatically improve the alfalfa's ability to resist the infection. Late August seedings are very susceptible, with mid-August plantings being intermediate.
In a no-till situation, minimize competition from existing weeds by applying a burndown application of glyphosate before planting. Using no-till when herbicide-resistant weeds are present creates a very difficult situation with no effective control options, so tillage is probably a better choice in those situations. Post-emergence herbicide options exist for alfalfa. After the alfalfa is up and growing, control late summer and fall emerging winter annual broadleaf weeds.
For conventional tillage seeding prepare a firm seedbed to ensure good seed-to-soil contact. Be aware that too much tillage depletes soil moisture and increases the risk of soil crusting. Follow the "footprint guide" that soil should be firm enough for a footprint to sink no deeper than one-half inch. Tilled seedbeds do not need a pre-plant herbicide. The recommended seeding depth for forages is one-quarter to one-half inch deep. It is better to err on the side of planting shallow rather than too deep.
This article originally appeared on The Daily Record: Soybean growers to scout for stink bugs
