Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32M A R C H 2 0 1 7 26 POTATO GROWER Dying Syndrome. A survey found high numbers of P. penetrans, P. scribneri, P. neglectus and others. It is challenging to identify P. penetrans using the traditional microscopic method, because there are only minor morphological differences between the species. Therefore, she developed a qPCR Assay to identify and quantify P. penetrans in soil and designed new species-specific qPCR primers to identify P. penetrans. She developed a qPCR assay to quantify this species directly in DNA extracts of soil. She found that the PCR assay is a useful tool for efficient detection and quantification of P. penetrans from field soil. It required no expertise in nematology. Dr. Carl Rosen, UMN, gave his report on the nitrogen response and soil microbial activity in potato cropping systems as affected by fumigation. He indicated that soil- borne diseases in potato are a major challenge because these diseases build up even with proper rotation. Fumigation is used to control soil- borne diseases giving healthier roots by reducing root infecting microbes. However, fumigation also elimi- nates beneficial organisms and dis- rupts nutrient cycling and soil health, which is one of the reasons that diseases will return. Dr. Rosen claimed that once fumigation is used, further fumigation is usually required whenever potatoes are grown. This year’s research was to determine how fumigation affects potato response to nitrogen fertiliz- er application and to characterize the effects of fumigation on micro- bial activity and nitrogen transfor- mations. Soil health tests were used to determine microbial activity to evaluate the effects of fumigation on disease incidence. The Solivta CO2 Burst Test is a newly commer- cialized test kit. They learned that fumigation with Vapam and Chloropicrin resulted in a 50-60 cwt/A increase over the controls and that the microbial activity was reduced with fumigation. They also found that microbial activity decreased during the growing sea- son in all treatments. Their instru- ment of measuring was the “CO2 burst test”. However, this is generic and does not differentiate between pathogenic and nonpathogenic microbes. That means that a higher activity may not necessarily be good if pathogens are present. They also noticed that the optimal N rate was not higher in non-fumigated plots than fumigated plots. Dr. Rosen indicated that when the crop dies, a little bit of extra N does not help to increase the yield. On the contrary, they saw that increasing N rate actu- ally resulted in lower yields. It was clear that fumigation disrupted nitrogen transformations. They measured higher ammonium in fumigated plots. Dr. Rosen conclud- ed that Chloropicrin had a greater effect than Vapam. To answer the question, how does a planting delay affect potato yield from sub-lethal doses of glyphosate and dicamba?, Dr. Hatterman- Valenti, NDSU, did research on the effects of glyphosate and dicamba at tuber initiation, when they do most current season damage. It became evident that off-target injury from dicamba poses a greater threat to potato than glyphosate. They found that high rates of Dicamba with or without high rates of glyphosate caused most damage. It was also clear that environmental condi- tions, especially those during and following a drift incidence can greatly influence herbicide injury and yield reduction. One result was that planting delays can further confound expected results from a drift incidence. It is important to know that dry beans are much more sensitive to dicamba off-target movement than potatoes or dry peas. Mr. Nelson Geary, NDSU, studied the effects of glyphosate & dicamba residues in seed potatoes that were planted back. He came to the con- clusion that seed potatoes that were contaminated with very low dosages of dicamba and glyphosate produced a much lower yield due to germination inhibition. He suggest- ed to be very careful when spraying dicamba and glyphosate near potato fields. Ms. Upasana Ghosh, NDSU, was the last speaker with her report on the performance of enhanced efficiency fertilizers in delayed planting of irri- gated russet potatoes. She found that ESN showed consistent yield maintaining capacity over two con- secutive years. It reduced NH3 volatilization, N2O emission and NO3- leaching compared to Urea. The most positive effect was in inde- terminate varieties. A different N fertilizer rate and management pro- gram should to be developed for determinate cultivars was her con- clusion. The meeting was well organized and was attended by over 180 growers and potato industry people.