COL Iron chlorosis shows up in soybeans

Cool early summer temperatures have promoted soybean iron chlorosis development, says Jim Nesseth, Extension educator in southwestern Minnesota. Yellowing soybeans caused by iron chlorosis has always been a problem, and it is a problem for some growers again this season.

Iron chlorosis usually first shows up in low and wet field areas. Patches of soybeans may turn yellow in low areas. Brown and necrotic spots may occur in leaf margins and plants can be stressed or killed if the disease is severe.

The symptoms are more pronounced when soil temperature is low and soil moisture is higher. Often, plants with iron chlorosis suffer from fungal root rot problems or soybean cyst nematodes, he said.

If iron chlorosis is a problem this year, consider management options in next season's crops.

Wheat stem maggot makes return


Wheat growers will be seeing an enemy that hasn't shown up in years, says Joe Neubauer, McLeod County (Minn.) Extension educator.

The name of the culprit is wheat stem maggot. It's an insect that causes wheat heads to turn white, Neubauer said. It is greenish-white and can be found inside the stem just above the top node. The adult is a small yellowish-blackish fly.

The damage caused by the insect is very noticeable, Neubauer said. If white wheat heads are found and can't be connected with some other problem, collect stems and cut them open just above the top node. Either the tunnel or the maggot itself will be seen.

The heads can easily be pulled from the sheath. Rarely does the infestation get above 5 percent of the field, although it may look worse.

Dairy management has new publication

Dairy cow longevity, health and forages are the subjects of a new publication offered by Midwest Plan Service.

The publication contains proceedings from a recent professional dairy management seminar held in Dubuque, Iowa. The conference involved faculty from the University of Illinois, Iowa State University, the University of Minnesota and the University of Wisconsin.

Cow comfort, extending longevity through genetics and the relationship between lameness and longevity are topics of the publication, which also includes management papers on silage in bunkers, trenches and piles and silage particle size.


"Four-State Professional Dairy Management Seminar,'' MWPS-4SD13, is available for $19.70 for Minnesota residents and $18.50 for Iowa residents. It can be obtained by telephoning 1-800-322-8642.

Fireblight may hit apple trees

This may be a banner year for fireblight disease in apples, says Dave Schwartz, Meeker County (Minn.) Extension educator. In one out of 10 years, blight causes serious damage to apple trees and other plants such as cotoneaster, mountain ash, pear and flowering crab.

In 1978, Schwartz said, apple blight hit Beacon, Fireside, Honeygold, Wealthy and Connell Red apple trees. Resistant varieties such as Haralson stood up well against the blight. Fireblight is a bacterial disease that is aided by heavy rains, hail and warm, humid weather.

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