ISSUE 7 June 24, 2010
North Central ND
Moderate to severe infections of tan spot are common throughout the area. Winter wheat that is heading has a moderate risk for scab infections. Stripe rust was observed on winter wheat. The triazole fungicides that control scab are also very effective against stripe rust (Marcia McMullen, Extension Plant Pathologist). Consider using the full rate of fungicide under the high disease pressure that we have been experiencing this season. A four ounce rate of propiconazole (Tilt, PropiMax, Bumper) will provide control up to 20 days as compared with 10 day control with a 2 oz. rate (Marcia McMullen, Extension Plant Pathologist).
Peas, Lentils, and Chickpeas:
Peas and Lentils are beginning to bloom in some areas. Fields should be scouted during full bloom for pea aphids and Lygus bugs. We continue to see pea aphids in pea and lentil fields and have begun seeing Lygus bugs. Lygus bugs cause a problem known as chalk spot in peas and lentils. Bacterial blight and root rots are prevalent throughout the area. As the temperatures rise, bacterial blight will dry up and no longer be a problem (Sam Markell, Extension Plant Pathologist). There have also been reports of Ascochyta in chickpeas and field peas. A key fungicide timing for this disease is at bloom. Resistance management should be employed by rotating fungicides with different modes of action (www.ag.ndsu.edu/pubs/plantsci/smgrains/pp1362.pdf).
Lygus bugs have been caught in blooming canola fields. At average application costs and canola prices, canola should be treated for Lygus bugs from bud stage through flowering (petal drop) if more than 15 bugs are caught in 10 sweeps (1.5 bugs/sweep). Please refer to the following website for more specific information including different thresholds for cost and price variation: www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex741
Diamondback moth (DBM) larvae have been found in a blooming canola field at the North Central Research Extension center. Canola is most susceptible to injury from DBM at bloom to early pod development. Insecticide applications are justified when two or more larvae per plant are found throughout a field. For more information see: http://www.ag.ndsu.edu/pubs/plantsci/pests/e1346.htm
The risk for flea beetle damage has passed because the vast majority of fields in the area are near or beyond the six leaf stage.
Sunflower beetle adults and larvae were found by our IPM scout, Asanga Manamperi, in low numbers in a field in the area. Insecticide seed treatments have done a good job of reducing populations of this pest in recent years. However, as with other insecticide seed treated crops, the effect of the insecticide diminished a few weeks after planting.
Sunflower rust was found in a field in western Bottineau County. Orange circular pustules were observed on cotyledons and on young leaves. Early infections are of particular concern and advance rapidly with daytime temperatures in the 80ís and/or night time temperatures in the 70ís.
For more information see: www.ag.ndsu.edu/pubs/plantsci/rowcrops/pp998.pdf
IPM specialist - North Central Research Extension Center
According to NDAWN (North Dakota Ag Weather Network) data, the region received 0.3 inch (Fingal) to 1.8 inch (Carrington) of rain during June 16 to June 22. The regionís soil moisture continues to be at adequate to excess levels. June 17-18 high winds and rainfall caused some crop damage or loss.
Alfalfa harvest continues between rainfall events. Pasture growth and re-growth of first-cut alfalfa is excellent. Winter wheat is in the seed-fill growth stages. April-seeded small grain is the boot to flowering stages. The continued moderate temperatures and adequate soil moisture is preserving yield potential in small grain. Fungicide use should be considered to prevent flag leaf damage from leaf spot disease and to reduce risk from scab (Fusarium head blight). Timely-planted corn is in the 5- to 7-leaf stage.
Accumulated growing-degree day units for April 25 planted corn to June 22 ranges from 20 units at Fingal to -70 units at Linton compared to the past 5-year average. Some of the regionís corn will be waist high by July 4. Weed spraying continues in row crops. Some soybean planting continues but most timely-planted soybean is in the 3-trifoliate leaf stage. Soybean flowering is expected around July 1. Cool-season broadleaf crops are in the flowering to early-pod development stages including canola, field pea, and flax.
Numerous calls are being received regarding increasing wheat protein with late-season application of nitrogen. Refer to Dave Franzenís articles in previous issues of the ĎCrop and Pest Reportí. Please contact NDSU agronomists or extension agents if you need additional details on this strategy.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center