Chemicals alone usually apply chemicals at least twice: pre-plant and pre-emergence
preemergence and postemergence more feasible now than prior to the mid1980's due to the advent of new postemergence herbicides
- poast grassy weeds fusillade grassy weeds
- basagran broadleaf weeds
- roundup wick system

Round-up Ready fields require 1 to 2 applications

Weed problems in WI

Black nightshade berries plug the sieves
Smartweeds plug the reel and knock beans down bean plants may hook onto smartweeds on the reel and may eventually fall to the ground
Volunteer corn may reduce yields and market grade

Insects

Basic Plan for Scouting Soybean Insects in the Corn Belt

Crop emergence: early season insects like bean leaf beetle
June and July: mid-season defoliators like bean leaf beetle, green clover worm, Japanese beetle. Also sap suckers like two spotted spider mite
July and August: late-season defoliators and pod feeders like lean leaf beetle and grasshoppers

Soybean Aphid

Diseases

Conditions necessary for disease development:

Host (susceptible)
Pathogen (virulent)
Environment (favorable)

Control measures influence all 3 factors

Resistant host crop variety has a gene or genes for resistance
Control the environment of the pathogen
- Rotations bury crop residues and eliminate alternate hosts
- Row spacing
- Plant density
Control the pathogen via chemicals
- seed treatments: apron vitavax
- foliar fungicides: benlate (soybeans) topsin
- soil fungicides: ridomil

Management effects on disease

Soybean diseases common in Wisconsin

Summary of relationships among management practices and soybean diseases. Craig Grau, University of Wisconsin
	Brown Stem Rot	White Mold	Phytophthora Root Rot	Soybean Cyst Nematode	Seedling Blight
Early Planting Date	Negates benefits	Greater severity and yield loss	Greater seedling mortality	Greater invasion of roots, unknown yield effect	Greater in cool-wet soils
High Plant Population	Negates benefits	Greater severity and yield loss	Unknown	Unknown	May compensate for seedling mortality
Narrow Row-Width	Negates benefits	Greater severity, negates yield advantage	Unknown	Unknown	Unknown
Fungicide- treated seed	No documented effect	No documented effect	Apron® effectively reduces seedling mortality phase	None available	Apron®, Rival® effective; respond to no-till and early planting date systems
Crop rotation schemes	2-3 years of nonhost extremely effective. Improves yield of both resistant and susceptible varieties.	2-3 years of nonhost beneficial, but rotation effect improved by planting less susceptible varieties.	Limited value	2-3 years of nonhost beneficial. Improves yield of resistant and susceptible varieties.	Limited value
No tillage	Greater severity and yield loss	No-till in nonhost year enhances death of Sclerotinia sclerotia.	Greater severity and yield loss	Lower SCN population, greater yield	Greater severity and yield loss
Soil fertility and tilth	Higher K and pH, and supplemental N, reduce severity and improve yield	High fertility, dense canopy result in greater severity and yield loss.	Additional N results in greater severity and yield loss	Minimal effects. High K may be beneficial	Compaction results in greater severity and yield loss
Weed management	Modest suppression by Pusuit® herbicide	Significant suppression by Cobra®. Disruption of sclerotia by atrazine. Disruption of sclerotia by cultivation.	Unknown	Suppression of SCN reproduction by Blazer® herbicide.	Preemergent herbicides suspected of reducing seedling vigor resulting in greater seedling mortality.

Phytophthora root rot

Usually occurs in poorly drained areas of a field

Infects roots and stems, usually early in the growth of the soybean plant
Infected plants turn light green due to root infection, plant growth is uneven, lower stems turn brown, and leaves eventually wilt and die
There are at least 27 known types or races of prr in Wisconsin

Control measures for Phytophthora root rot

identify race(s) present: can do this in Wisconsin by submitting samples to a UW extension office
grow a variety that is resistant to the race(s) present
cultural practices improve soil drainage rotate with cereals minimize soil compaction if cultivating, ridging soil around the base of plants may help
this stimulates new root growth from lower stem
chemical treatments (apron and ridomil)

Brown stem rot

Widespread in northern soybean growing area of the Midwest (Illinois, Iowa, Minnesota, Wisconsin)

difficult to identify because it usually develops late in the season
inside of lower stem turns brown
leaves die prematurely, often confused with early maturity
disease is spread in crop residue

Control measures

rotate with a cereal
resistant varieties

Pod and stem blight

Infects stems and pods of plants as they near maturity

small black spots (pycnia) on stems and pods
spots are in rows on stems
spots are scattered on pods

Disease is seedborne and also overwinters on residue

Control:

plow refuse under rotations plant seed from disease
free fields because infected seed often has low germination most soybean diseases don't have a major effect on seed quality, but pod and stem blight does.

Soybean Pests

Weeds