Disease Management In Irrigated Row Crops Melvin A. Newman, Ph.D. Professor University of Tennessee Extension Entomology and Plant Pathology Dept. Jackson, TN
6 Soybean Disease Loss Estimate for Tennessee, 2007-11 16 % in 07, 14.8% in 08, 29.7% in 09, 17.1 % in 10, 14.3 % in 11 five-year average loss = 8 million bushels/year % YIELD LOSS 5 4 3 2 1 5-year average loss = 18.4 % Rust damage =.01% in 09 % Loss 07 % Loss 08 % Loss 09 % Loss 10 %Loss 11 0 FROGEYE CYST N. ANTHRAC BR. SPOT SDS SEEDLING CHAR. ROT PURPLE STAIN SEED ROT STEM C. PHYTOPH. P&S BLT.
Charcoal rot (Macrophomina phaseolina)
Charcoal rot (Macrophomina phaseolina)
Microsclerotia Charcoal rot (Macrophomina phaseolina)
Charcoal Rot Management Keep soil moisture high with irrigation, especially during late reproductive stages. Avoid high seeding rates. Rotate with less susceptible crops cotton Maintain good fertility levels. Plant varieties and maturity groups that mature before late season drought. Plant as early as possible for good growth. Resistant varieties are being researched.
Stem Canker Susceptible Resistant
Canker Brown Pith Stem Canker (Southern) (Diaporthe phaseolorum var. meridionalis)
Stem Canker Control Plant resistant varieties. Later planting may help. Rotate with other crops. Treat planting seed with fungicide. Irrigation at V3 V? or frequent rainfall will increase chances on susceptible varieties
Sudden Death Syndrome (SDS) (Fusarium solani f. sp. glycines) SDS Healthy White pith
SDS on leaves
SDS Control Plant resistant varieties. Keep soil Potash levels high. Rotation with corn does not help. Higher plant populations may help some. High organic matter and moisture increases SDS. Reduce Soybean Cyst Nematode levels. Delayed planting and early maturing varieties may lessen SDS severity. Irrigation and rainy weather will increase severity on susceptible varieties.
Phytophthora Rot (Stem girdling lesion) Brown discoloration
Phytophthora Rot Control Some varieties may have some resistance. Many different races. Improve drainage and soil compaction. Early irrigation may increase this disease Crop rotation may improve control. Treat seed with metalaxyl fungicide (Apron). Animal manure and high potash level may increase the disease.
Septoria brown spot (Septoria glycines) Early season pycnidia
Brown Spot (Late season)
Severe Brown Spot at WTREC Overhead irrigated No Spray No Spray Fungicide HeadlineSprayed @R3
Anthracnose Late season
Frogeye leaf spot
Frogeye leaf spot
Frogeye leaf spot
Frogeye leaf spot
Seedling Disease Control Fungicides Made Simple Cool season pathogens: Pythium and Phytophthora controlled by: Metalaxyl and Mefenoxam (same basic chem.) Warm season pathogens: Rhizoctonia and Fusarium controlled by: Pyraclostrobin, Trifloxystrobin, Ipconazole and Fludioxonil
Some Soybean Seed Treatment Fungicides ApronMaxx: Mefenoxam + Fludioxonil Trilex 2000: Metalaxyl + Trifloxystrobin Acceleron : Metalaxyl + Pyraclostrobin Escalate: Metalaxyl + Ipconazole + Thiram Rancona Summit: Metalaxyl + Ipconazole Pioneer Premium: Metalaxyl + Trifloxystrobin
Foliar Disease Control (FLS, Brown Spot, Anthracnose, etc.) FLS Plant resistant varieties. Rotate with other crops. Use foliar fungicides when disease is likely to occur. Keep fertility and ph at recommended levels. Treat planting seed with fungicide. Irrigate during the AM as much water as possible at one time. Use irrigation to apply foliar fungicide.
Soybean Rust Pustules
Soybean Rust Control There are no resistant commercial varieties. Spray a recommended fungicide (Triazole) on a timely basis when the risk is high for infection. Planting early in TN, may avoid severe infection coming late in the season? Irrigation will increase chances for rust development if spores are present.
Sprayed Untreated
Soybean Cyst Nematode Few Nitrogen Nodules Rotted roots Cysts
Race 2 SCN infestation Sept. 2008
Soybean Cyst Nematode Race 2 infested field near Jackson, TN
nematodes on young root Growing point
Embedded White Female Cysts Rotted Soybean Root
Soybean Cyst Nematode (21 day life cycle) Mature female cyst (50-200 eggs/cysts) Egg Mass (50-200 eggs) Root UT/MAN
Soybean Cyst Nematode Control First, determine the level of infestation. 100 Cyst per pint of soil is a general Economic Threshold If you have race 2, there are no RR commercial varieties that have good resistance. Anand and JTN 5203 (new release) are resistant, but not RR. Rotation reduces the level of SCN, but while not eradicate SCN. 75 % reduction in nema population the first year. Keep potash levels high. Wet weather or irrigation may increase populations for the next season. No-till and later plantings may reduce population levels. Use of nematicides may help to increase yield, but will not reduce the population levels at harvest. Some seed treatments may help.
Diseases to Consider with Overhead Irrigation Diseases to watch for: Frogeye leaf spot Brown Spot Anthracnose SDS Stem Canker Cyst Nematode Soybean Rust Best Control Resistant var. or F.F. Foliar Fungicide Foliar Fungicide Resistant var. Resistant var. Resistant var. Rotation Foliar Fungicide Less possible Diseases Charcoal Rot Best Control Irrigation
Gray Leaf Spot (GLS) Control
Early Lesion of Gray Leaf Spot Lesions run parallel with veins
Gray Leaf Spot caused by Cercospora zeae-maydis
Gray Leaf Spot Control Use tolerant varieties if available. Rotate crops. Plow under crop residue in fall if conventional tillage. Foliar fungicides increase yields if sprayed before disease hits. Irrigate with more water and less frequently in AM Plant as early as possible. Follow all good agronomic practices. Apply fungicide with irrigation rig.
Thank you Any Questions???