Potato Extension
Blightline August 4, 2014
Late blight has not been reported in our region of ND, MN or MB. The late blight severity threshold value of 15 has been reached at all locations except Williston. For our conditions, application of a protectant fungicide such as mancozeb or chlorothalonil on a 7-10 day schedule is recommended.
Aphid Alert up to August 1
Aphid counts were down this week over last with only the Ada site reporting more than 10 vector species individuals. Even numbers of non-vector aphid species were down this week, indicating that aphid flights were suppressed but warmer temps, especially nights, may well drive numbers higher (or then again, maybe autumn is coming - nothing would surprise me about this summer!). Bird cherry oat aphids were again the most numerous vector species and was recovered from 13 of the 18 sites reporting. No green peach aphids or soybean aphids were recovered in any trap but green peach aphids were found in our greenhouse on potted potato plants. We suspect they were already present in low numbers and the warmer days increased their reproductive rate in the greenhouse.
Blightline July 28, 2014
Late blight has not been reported in our region of ND, MN or MB. The late blight severity threshold value of 15 has been reached at all locations except Beach, Leonard, and Williston, which are at 13, 10 and 14 respectively. Weather conditions at all sites except these three have accumulated sufficiently for late blight to occur if inoculum is present, and application of a protectant fungicide such as mancozeb or chlorothalonil should be applied on a 7-10 day schedule is recommended.
Aphid Alert
A new Aphid Alert is now available at aphidalert.blogspot.com or aphidalert.umn.edu. This includes trap catches from sites up to July 18th. Aphid numbers are increasing, but most are bird cherry oat aphid and green bug. Please go to Dr. MacRae's webpage for more information.
Blightline July 24, 2014
No late blight has been reported in our region. The recent storm caused late blight severity values to increase quickly the past three days. The threshold value of 15 has been reached at all locations except Beach, Leonard, Williston, Grand Forks and St. Thomas. At the severity value threshold of 15, weather conditions have accumulated sufficiently for late blight to occur if inoculum is present. Application of a protectant fungicide such as mancozeb or chlorothalonil on a 7-10 day schedule is recommended.
Blightline July 21, 2014
No late blight has been reported in our region. Late blight has been reported in potatoes Portage County, Wisconsin; the late blight is not widespread. Late blight severity values generally did not increase over weekend. If severity values in your area have accumulated to 15, application of a protectant fungicide such as mancozeb or chlorothalonil on a 7-10 day schedule is recommended. Many sites have reached this threshold.
Blightline July 17, 2014
No late blight has been reported in our region. Late blight severity values did not increase the past three days. If severity values in your area have accumulated to 15, application of a protectant fungicide such as mancozeb or chlorothalonil on a 7-10 day schedule is recommended. Many sites have reached this threshold. P-day values, an indicator or early blight, are approaching 250-300 in many areas, and growers should consider application of an early blight fungicide and scout for the presence of early blight. Growers and scouts have reported that very little early blight is present now. The cool weather does not favor development of early blight.
Blightline July 14, 2014
No late blight has been reported in our region. Late blight severity values generally increased slightly over the weekend. The cool weather forecast for next week is favorable for late blight. If severity values in your area have accumulated to 15, application of a protectant fungicide such as mancozeb or chlorothalonil on a 7-10 day schedule is recommended. Many sites have reached this threshold.
Aphid Alert, July 11
We're getting vectors at a few more locations but still seeing low numbers. Nine of the sites from which we received trap catches had at least one aphid vector. High counts were at our Linton sites with three and four vectors. Ada, Erskine, Forest River, Hallock, Hoople, Langdon, and Staples collected no vectors. Species captured include buckthorn, bird-cherry oat, green bug, english grain, sunflower, cowpea, and pea aphids. These are all medium efficiency vectors.
MN Area II Potato Field Day set for July 15
The MN Area II Potato Council Field Day is set for July 15 at 5:30pm at the Sand Plains Research Farm in Becker, MN. Research and Extension personnel from North Dakota State University and the University of Minnesota will be discussing research and answering questions. Come and learn about ongoing research in potato agronomy, breeding, entomology, nutrient management, pathology, and other important topics.
Document Actions
