Issue link: http://read.uberflip.com/i/945399
36 POTATO GROWER | MARCH 2018 Diggin' In Diggin' In Diggin' In Diggin' In Diggin' In Diggin' In DISEASE CONTROL | By Phillip S. Wharton & Kasia Duellman, University of Idaho Pre- and early-season control measures for potato diseases Early Start Seed-borne diseases of potato represent a significant constraint to potato production in the U.S. Pathogens such as Fusarium sambucinum (Fusarium dry rot) and Phytophthora infestans (late blight) are major potato pathogens, affecting tubers in storage and seed tubers and sprouts after planting. In severe outbreaks, the pathogens may completely rot seed pieces or kill developing sprouts outright, resulting in delayed or non-emergence. The use of an effective seed treatment in combination with good management practices during cutting and seed storage prior to planting is essential to reducing Fusarium dry rot and preventing late blight, as well as secondary bacterial soft rot. Contact Shaun Lough to learn more: (509) 669-7600 • slough@westbridge.com PRODUCT BENEFITS: • Stimulates seedling vigor • Improves specic gravity • Enhances tuber development • Increases uniformity & yield Always use Soil TRIGGRR® as part of a complete fertility program. Maximize Crop Production Discover the benets of our complete line of products. Call today for more information. ® www.westbridge.com ® FOLIAR Plant Growth Regulator ® SOIL Plant Growth Regulator 171635Westbr13s.indd 1 1/23/18 3:03 PM Good management practices begin with the control of volunteer potatoes (those left in the field during the previous season's harvest and have survived the winter). Volunteer potatoes have become an important perennial weed in many potato- growing regions. Potato sprouts emerge from overwintered tubers and grow rapidly in the spring. This rapid growth, combined with the tuber's ability to re-sprout, makes them very difficult to control, even with multiple control measures. Volunteer potatoes act as hosts for a number of important pests and diseases, including late blight, Colorado potato beetle, potato leafroll virus, potato virus Y and nematodes such as stubby root nematode (which transmits tobacco rattle virus, the causal agent of corky ringspot disease). Winters in the northern U.S. have become warmer over the last few years, which may favor overwinter survival of volunteer and cull potatoes. With the recent trend for warmer winters, more volunteers and cull pile potatoes are surviving the winter and acting as sources of disease inoculum in the spring. Cull potatoes are those potatoes deemed unusable for the fresh market, processing or dehydration, or disposed of for some other reason, such as overproduction or waste (slivers) from seed production. Research has shown that the temperature within discarded cull piles may influence core tuber tissue temperatures affecting the survival of tuber tissue and thus P. infestans mycelia in infected tubers. Consequently, the risk of initiation of an epidemic of late blight from cull piles is closely related to the temperature experience of overwintered potato culls. Although the potatoes at the top and bottom of a cull pile may freeze over the winter when ambient air temperatures fall below freezing,