Adam Sisson

Corn yield loss estimates due to diseases in the United States and Ontario, Canada from 2012 to 2015.

Annual decreases in corn yield caused by diseases were estimated by surveying members of the Corn Disease Working Group in 22 corn-producing states in the United States and in Ontario, Canada, from 2012 through 2015. Estimated loss from each disease varied greatly by state and year. In general, foliar diseases such as northern corn leaf blight, gray leaf spot, and Goss’s wilt commonly caused the largest estimated yield loss in the northern United States and Ontario during nondrought years. Fusarium stalk rot and plant-parasitic nematodes caused the most estimated loss in the southernmost United States. The estimated mean economic loss due to yield loss by corn diseases in the United States and Ontario from 2012 to 2015 was

Assessing new methods of integrated pest management for apple orchards in the Midwest and phenology of sooty blotch and flyspeck fungi on apples in Iowa

76.51 USD per acre. The cost of disease-mitigating strategies is another potential source of profit loss. Results from this survey will provide scientists, breeders, government, and educators with data to help inform and prioritize research, policy, and educational efforts in corn pathology and disease management. M U E L L E R E T A L . , P L A N T H E A L T H P R O G R E S S 1 7 (2 0 1 6 )

Testing for Plant-parasitic Nematodes that Feed on Corn in Iowa 2000-2010

Sooty blotch and flyspeck (SBFS) is a complex of >60 fungal species that blemish the surface of apple fruit in humid regions worldwide. Blemishes become visible in mid-to late summer, reducing the value of fresh fruit. To test the hypothesis that SBFS species appear on apples at characteristic times during the growing season, 22-37 apples were monitored weekly for appearance of SBFS colonies at each of three Iowa orchards in 2006 and seven orchards in 2007. Colonies were marked with colored pens to denote the date of appearance. After harvest and storage of apples at 4° C for 3 months, SBFS colonies on each fruit were counted and classified by morphology, and a representative subset of colonies with subtending peel was removed and pressed. Fungal DNA, extracted from colonies scraped from the surface of the peel, was amplified with primer pair ITS1-F/ Myc1-R. Polymerase chain reaction products were digested with HaeIII, and fragment patterns were observed with gel electrophoresis and compared to a library of previously identified SBFS species. Colonies

Temporal Patterns in Appearance of Sooty Blotch and Flyspeck Fungi on Apples

The Iowa State University Plant and Insect Diagnostic Clinic analyzes soil and root samples for plant-parasitic nematodes. The results of samples associated with corn that were submitted from 2000 through 2010 were summarized. One or more genera of plant-parasitic nematodes were found in 92% of the samples. Spiral nematode and root-lesion nematode were most commonly found. Other nematodes recovered were dagger, lance, needle, pin, ring, and stunt nematodes. Nematodes recovered at damaging population densities were dagger, needle, ring, and spiral nematodes. An average of 15 samples were submitted per year from 2000 to 2004. Sample numbers increased nearly threefold since 2005, but overall sample numbers were low every year from 2000 through 2010. Samples were received from 53 of the 99 Iowa counties, and most samples were received in June and July, which is the recommended sampling time. Nematodes that have been associated with corn in Iowa in the past that were not recovered from the samples were sheath, sting, and stubby-root nematodes. The methods used to extract the nematodes from soil and roots and how the samples were handled during collection and processing may have affected the species and population densities recovered. Much more frequent and widespread sampling is needed in Iowa for plant-parasitic nematodes that feed on corn.