iris yellow spot virus and downy mildew
Iris yellow spot virus has been positively identified on onions planted for seed. The onions were planted last year, and the virus symptoms are typical of scape lesions usually associated with IYSV on seed onions (click on image below). Bulb onion growers should be aware that the virus is likely in all overwintered onion seed fields, and should aggressively manage onion thrips in fields located near seed fields, particularly those fields located down wind from the seed fields.
In addition, downy mildew has been identified on the same onion scapes as the IYSV. This is highly unusual, and is likely due to the cool spring weather. If the weather cools to the mid 70's and we get summer showers, then there is a chance that the downy mildew could spread to the bulb crop. Applying a registered fungicide along with your thrips sprays may alleviate any potential problem. The following link will take you to the Oregon State University Extension website that contains images and control measures for downy mildew: http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=752.
Colorado potato beetle larvae
Colorado potato beetle larvae are now emerging from eggs in the Rupert area. Growers who have not put on an at-planting insecticide need to apply a foliar insecticide.
Malheur Experiment Station Field Day
The Malheur Experiment Station Field Day is July 9, 2008. The pdf files below contain the program for the day.
powdery mildew in sugarbeets
The Amalgamated Sugar Company Field Representatives are saying that now is the time to plan your treatments for powdery mildew in sugarbeets. While mildew has not yet been found in the Treasure Valley, White Satin Field staff say the modes of action of the mildew chemistries work best if treatments are applied before mildew is found in the field. They are recommending mildew applications in the west end of the Treasure Valley the week after July 4 regardless of whether or not your fields are surface or sprinkler irrigated. You may also want to include an insecticide treatment for black bean aphid or loopers in the mildew tank mix. CONTACT YOUR WHITE SATIN FIELD REPRESENTATIVE FOR INFORMATION REGARDING THESE TREATMENT RECOMMENDATIONS AND ROTATION OF CHEMISTRIES.
stripe rust in wheat
The following information was provided by Dr. Brad Brown from the UI Parma R and E Center.
It appears that Treasure Valley wheat has gone yet another year without significant stripe rust incidence. The only stripe rust we are aware of in western Idaho thus far is a small infection (less than 5%) in a susceptible hard red winter wheat variety called Moreland. It is the only wheat variety of those we evaluate in both the Extension winter and spring wheat variety performance trials that we have found any rust in. Varieties commonly grown in the area do not appear to be susceptible to the stripe rust race infecting Moreland. Even Brundage soft white winter wheat, known to be less tolerant to stripe rust than Stephens, looks pretty clean on the Parma R & E Center.
Scouting for stripe rust is still a good policy, especially for spring plantings that are slower to develop. Development of both winter and spring wheat is later than normal this year. Even though some fields may have been treated much earlier with tank mixes of fungicides and herbicides, that does not preclude infection during latter grain filling.
Some winter wheat planted after wheat is showing significant root rot. The symptoms include heads that are maturing earlier than those around them, and are poorly filled or blank. The root systems of plants dug up, when rinsed with water, generally show limited root growth or roots browned from fungal infection, sometimes encrusted with fungal mycelium that does not wash off readily. The crown tissue, instead of white to cream colored, can show browning or blackened deterioration. The symptoms of some root rots do not necessarily show up on the lower stem. At this point of crop development the damage to the crop is done and there is no treatment for control.
Colorado Potato Beetle
A few Colorado Potato Beetle larvae are being found in the Greenleaf area. Growers should now be scouting for CPB larvae to time your foliar sprays.
UI Vegetable Field Tour
Vegetable Field Tour
Parma R & E Center
July 8, 2008 - 1:30 pm
Onions
• Early Banded Nitrogen Sources for Onions
• Thrips and Iris Yellow Spot Virus Control Strategies
• Effect of Application Volume on Thrips Control with Carzol
• Onion Powdery Mildew
Sweet Corn
• Cultivars for Direct Market Growers in the Treasure Valley
• Sweet Corn Seed Treatments
Potatoes
• Green Manures and Trap Crops for Potato Cyst Nematode Eradication
• Specialty Processing and Fresh Market Potato Cultivars
• Management of Stem Number
• Evaluation of Perform Leaf Growth Regulator
No RSVP is necessary to attend Vegetable Field Tour, just show up. Refreshments will be served.
Emmett Fruitgrower Lunch Meeting
June 25th: Fruitgrowers are invited to learn about Abiotic and Biotic Orchard diseases next Wednesday at 11:00am in Emmett at the La Costa Family Mexican Restaurant in Emmett. 517 N. Washington Ave. 365-1567.
Speakers: Essie Fallahi UI Pomology Specialist and Krishna Mohan UI Pathology Specialist. Tom Tankersley orchard Updates.