EDEN PRAIRIE, Minn. (DTN) -- As we climb further into the dog days of August, more pests and some weather-related diseases continue to be reported. Fortunately, incidences seem spotty, with no current severe or widespread issues.

GOSS'S WILT

Perhaps the closest thing to a growing regional issue may be this bacterial leaf blight disease. It has shown up a lot this past week, according to plant pathologists in Iowa, Nebraska and Minnesota. The disease appears to be widespread north of I-80 in Iowa, in many Nebraska counties and in several southern Minnesota counties. The warm, wet and humid weather conditions appear to be helping the disease progress rapidly in fields of more susceptible hybrids.

Unfortunately, there are no proven, in-season remedies yet for this bacterial wilt, which can cut yields by as much as 70 to 80 bushels. Iowa State University plant pathologist Alison Robertson reported that growers are trying several products such as Procidic, Kocide and Intercept (see her comments here http://bit.ly/…).

Aside from these product trials, current advice is to manage it with hybrid resistance, crop rotation, deep tillage after harvest and by controlling grassy weeds. This leaf blight is caused by bacterial pathogens that overwinter in infested corn residue. It enters plants through wounds caused by hail, wind, rain and blown sand. http://bit.ly/….

SPIDER MITES

August is the typical season for spider mites, and entomologists in Missouri, Indiana, Iowa, Ohio and Michigan are seeing more of these pests that thrive in hot, dry weather. We're hearing reports of insecticide application in Missouri to reduce numbers. Despite heavy rainfall in some areas that normally slows mites, the outbreak potential continues. High humidity for extended periods within the soybean canopy can increase beneficial fungi that can infect and rapidly wipeout mites. http://bit.ly/….

SOYBEAN APHIDS

Soybean aphids have increased above economic thresholds in several areas of North Dakota. Other states are reporting varied aphid numbers, but not many are screaming for the need to spray. Every field is different and scouting is the only way to determine if a field has reached economic threshold (average 250 aphids per plant with an 80% incidence in the field).

Entomologists hope to see an increase in the incidence of pathogenic fungi that suppress aphids under cool, wet and humid conditions. If the soybeans are well into the R stages (R4-R5), the canopy is full and moisture is adequate, beans can easily handle the current levels of aphids and wouldn't get sprayed unless numbers increase dramatically.

STINK BUGS

Increasing reports of these pests are occurring in Nebraska. So far, entomologists are not reporting economically damaging populations this year to corn or soybeans. http://bit.ly/…

SDS/PHYTOPHTHORA

Wet areas of southern and central Minnesota are showing greater incidence of sudden death syndrome and Phytophthora root and stem according to plant pathologists. These soybean diseases appear to be spreading farther north every yearhttp://bit.ly/…. Similar reports of these diseases are also being reported in Missouri http://bit.ly/….

Kurt Lawton can be reached at kurt.lawton@telventdtn.com

(AG)

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