on nutrient media. In this test, the palea are removed 

 from the seeds, the caryoposis is surface sterilized and 

 bisected, and the halves are plated on malt-extract 

 agar (Neill and Hyde 1942, Calvert and Muskett 1945, 

 Muskett 1948). 



Preharvest Testing 



Preharvest testing of blind seed was common during 

 the 1940s in New Zealand (Scott 1974) to determine 

 if the ryegrass seed crop should be harvested. Greenall 

 (1943) sampled seed heads 2 weeks before harvest and 

 found good correlation between the percentage of seed 

 not infected (healthy seed) and germination of ma- 

 chine-dressed seed. However, samples should be taken 

 within 1 week of cutting (Hyde 1942, 1945: Lithgow 

 and Cottier 1953; Munro 1978; Alderman 1988, 

 1991b). Infection can occur up to the time of cutting, 

 so samples collected too early could underestimate 

 postharvest infection levels. 



The number of seed heads believed to be representa- 

 tive of the area was reported as 50 (Wade 1949), 300 

 (Hyde 1945, Osborn 1947), or 400-500 (Lithgow and 

 Cottier 1953; Alderman 1988, 1991b). 



Outlook 



The past decade has seen considerable changes in the 

 management of grass seed as growers moved away 

 from open-field burning of postharvest residue. 



Current management practices generally include 

 baling and removing straw residue followed by flail 

 chopping any remaining residue. In some cases, 

 specialized flail choppers are used on the full straw 

 load. Some growers practice no-till planting. It is not 

 clear what long-term effect these practices will have 

 on development of blind seed disease. Weather's role 

 is significant. Several consecutive years of wet 

 weather during flowering could be highly favorable 

 for disease development. 



Surveys of blind seed disease conducted over the past 

 decade have established the presence of a low level in 

 Oregon. The recent appearance of a high level of blind 

 seed in some fields of tall fescue indicates the poten- 

 tial for development of the disease. The greatest risk 

 will come from residue management practices that 

 leave large numbers of seeds in the field. Practices 

 such as field cleaning or late harvesting in which 

 considerable seed shatter occurs will only encourage 

 the disease under favorable conditions. 



Although significant yield losses are possible, it is 

 important to keep in mind that there can be a signifi- 

 cant drop in seed value at relatively low levels of 

 infection. Germination rates below 90 percent can 

 significantly reduce the value of the crop. Thus, the 

 presence of only 5 to 1 percent blind seed can hurt 

 profits. 



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