The soybean Podworm (SPW) (Helicoverpa zea) feeds on many various grain and vegetable crops in a lot of america. SPW has many various names relying on which crop it’s feeding on. These names embrace cotton bollworm, tomato fruitworm, sorghum headworm, and mostly corn earworm. Typically SPW is a soybean pest of the southern US; nonetheless, relying on a number of elements, this species can turn into an issue in soybean fields additional north and east, making its presence felt in areas the place it isn’t often an financial pest.
SPW adults are moths which can be very robust flyers. They’re usually tan in coloration with a wingspan of round 1.5 in. A key identifier for the SPW moth is an simply seen black band on the entrance and rear wing ideas. Grownup feminine moths can lay greater than 500 pearly white eggs. Every egg is laid singularly, which is completely different than many pest worm species. Many different species lay their eggs in teams or clumps on host crops.
In a lot of the Midwest, corn is the first host of this pest. A number of the worms that infest our fields may have overwintered in our space. Nevertheless, a major variety of moths migrate into the Midwest from the south, every boosting the inhabitants of SPW. We usually expertise three generations of Helicoverpa zea in components of the corn belt. The primary era will primarily reproduce on corn by feeding on ear ideas in newly pollinated fields. A number of the second and third generations might then transfer out into soybean fields the place they are going to lay their eggs which is able to lead to pod-feeding harm.
SPW moths desire open canopied soybean fields to put their eggs. Subsequently, late-planted and double-crop soybean fields are usually at greater danger for SPW infestation. Relying on the climate, eggs will hatch roughly one week after they’re laid. Freshly hatched larvae are roughly 1/16 in. lengthy. After rising via 5 – 6 larval levels over just a few weeks’ time, a completely developed larva shall be roughly 1.5 to 1.75 in. lengthy earlier than forming a pupa. The larvae of SPW will differ in coloration from mild inexperienced to brown. They nearly all the time have darkish stripes down the size of their our bodies and all the time have distinguished, scattered spines.
Freshly hatched larvae will primarily feed on foliage, however they start to feed on pods of soybean crops as they get bigger. The larvae are aggressive feeders and rapidly enter the pod to feed on the soybean leading to direct yield loss. For this reason SPW is such a major pest after they infest soybean fields.
The best option to scout for SPW is to put a white drop material between two soybean rows and shake the crops onto the fabric. Financial thresholds are met when one to 2 SPW are discovered per linear foot of row. Through the years, I’ve seen many fields that wanted to be sprayed for this pest. Most often, vital harm/ yield loss had already occurred. SPW usually trigger harm to soybeans from the R1 via R5 progress levels. As soon as soybean crops attain R6, SPW feeding quickly winds down. You will need to stroll your fields incessantly to scout for the various completely different pests that scale back our yields. SPW, specifically, is simple to overlook. They’re very arduous to see, and more often than not, you received’t discover they’re current till after they’ve already precipitated vital harm. Many pesticides can be found to manage this pest if remedy is required.
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