M A R C H 2 0 1 9 22 POTATO GROWER 2019 NPPGA Annual Research And Reporting Conference by Willem Schrage The Northern Plains Potato Association organized its Research Reporting Conference at the Alerus Center, Grand Forks, North Dakota on Tuesday, February 19th. The moderator Dr. Andy Robinson, NDSU/UMN, hosted the meeting and was the first speaker. His topic was the Effects Of Soil Carryover Of Imazamox (Raptor) On Potatoes. Raptor is commonly used in dry bean production for weed control. Potato growers have concerns that imazamox carryover in soil is occurring when potatoes follow dry bean production. The evidence of carryover is slow row closure and reduced yields. Dr. Robinson mentioned the plant back restrictions on the label. He showed symptoms of carry-over such as yellow- ing of new growth, elongated leaflets that are wrinkled and can cup upward; leaflet tips develop a boat shape and reddening of veins. Tuber symptoms are cracking and poor growth. Some con- clusions from his trial were that there were no carryover problems without fumigation. The hypothesis is that fumigation may kill microbes that break down the Raptor in the soil. Dr. Ian MacRae, UMN, spoke about Beetles and Aphids Wins and Losses. He also gave some news on Colorado pota- to beetles and aphid vectors of PVY. He mentioned certain patterns of neoni- cotinoid insecticide resistance in Minnesota and North Dakota. Overwintering adult Colorado potato beetles emerge later in the spring. Late emerging adults, although susceptible to neonicitinoid, see a lower dosage due to their later appearance. That’s how selection occurs. Dr. MacRae empha- sized that people should apply: Insecticide Resistance Management. That means: One should not follow a seed treatment with a foliar insecticide of the same mode of action group. To control overwintered generations one should wait till reproduction of the insect allows susceptible genotypes to be passed on before applying insecti- cides. To control summer generations of adults one should apply in response to defoliation, while utilizing economic thresholds when possible. Pre-mix insecticides should only be used later in the season. Earlier application of pre- mix enhances resistance. Aphid Alert is still active. Collaborators send in the aphids from their suction traps. The aphis alert program has creat- ed a PVY Vector Risk Index to indicate potential level of virus transmission, because not all aphid vectors are created equal. Dr. Gary Secor, NDSU, gave a Dickeya Update. He said that the biggest prob- lem D. dianthicola. Pectobacterium atroseptica is still important. The quar- antine pathogen Dickeya solani was not detected in samples from recent potato soft rot outbreaks. The good news was that cases of Dickeya in seed lots reduced from 2014 to 2018, mostly east of the Mississippi, in Michigan, Wisconsin, New York and Maine. In 2018 there were only six samples from North Dakota and they were not posi- tive for Dickeya. Numerous seed lots originating in North Dakota were test- ed, without one positive for Dickeya. Dr. Secor stated that a post-harvest test is necessary to detect Dickeya in seed. He recommended: PCR test of 400 tubers per lot. Symptom expression being temperature dependent was more severe in trials in Florida than in North Dakota. Trials did not show spread by cutting and planting, but there was spread in field irrigation or rain water. There is no indication of plant resist- ance. Imported dahlia bulbs were tested and found to be infected with Dickeya. Dr. Secor concluded that Dickeya has not Highest R-Value Insulation Moisture Barriers Fire Proofing Flat Roofs The Insulation Place 14770 69th Place NE • Grafton, ND 58237 ▲ ▲ ▲ ▲ Urethane Spray-On Insulation Eliminates air infiltration & stops condensation Grafton (701) 352-3233 1-800-352-0620 Bismarck (701) 255-0025 1-866-425-0025 Website www.theinsulationplace.com