However, modern systemic fungicides such as 

 benomyl have proven effective as a seed treatment 

 (Hardison 1970, 1972; McGee 1971b). In New- 

 Zealand, seed treatment with fungicides has proven 

 effective and is recommended for control of blind 

 seed disease (Rolston and Falloon 1998). 



Planting 



Calvert and Muskett ( 1944) reported that seed samples 

 from fields sown with a high level of blind seed did 

 not on average show a higher rate of infection than 

 seed from fields sown with disease-free seed. Simi- 

 larly, de Tempe ( 1966) found no association between 

 severity of blind-seed-infected seed at planting and 

 subsequent level of infection at harvest. However, the 

 effect of infected seed introduced at the time of 

 planting depends on the method of planting and 

 planting depth. Hardison ( 1957) observed that maxi- 

 mum production of apothecia occurred when fields 

 too small for drill planting were planted by broadcast- 

 ing seed over the soil surface. When seeds are planted 

 more than one-half inch deep, apothecia have diffi- 

 culty reaching the soil surface (Hardison 1949. 1957). 

 Good preparation of the seed bed facilitates planting 

 at the proper depth and good coverage of seed 

 (Hardison 1949. 1963). 



Fields with heavy soils or poor drainage may be more 

 favorable for blind seed development because they 

 provide the prolonged moist conditions that are 

 favorable for production of ascospores. Good soil 

 drainage provides conditions that are less favorable 

 for apothecial production (Hardison 1949. 1963). 



Infected seed must undergo a cool, moist period for 

 about 8 weeks to induce the reproductive (apothecial) 

 phase of the pathogen. Wright ( 1956) found that when 

 seed was planted in spring, apothecial production did 

 not occur; the requirement for cold conditioning was 

 not met. Similar results were reported by Fischer 

 (1944), who detected no apothecia when seed was 

 planted in spring but found 75.6 apothecia per square 

 meter in fall-planted seed. 



Planting a susceptible first-year companion crop such 

 as L. temlentwn is not recommended because of its 

 potential to increase inoculum if seed becomes 

 infected (Hardison 1949. 1957. 1963). 



Time of Closing (Grazing) 



Crops in New Zealand that are closed to grazing very 

 early or very late in the season may yield a crop that 



escapes peak ascospore dispersal (Blair 1947). Early 

 closing was recommended in New Zealand by 

 Gorman (1940), Lithgow and Cottier (1953). and 

 Lynch (1952). 



Nitrogen Fertilization 



Numerous studies indicate a reduction in blind seed in 

 response to manure or nitrogen fertilization. 

 Chestnutt ( 1958) and Rutherford ( 1956) reported a 

 significant reduction in blind seed in manured plots, 

 compared with unmanured plots of perennial ryegrass. 

 Lynch (1952) and Lithgow and Cottier (1953) ob- 

 served that nitrogen improved yield and germination, 

 although the effect of nitrogen on blind seed was 

 uncertain. In a paired-plot experiment. Stewart (1963) 

 found blind seed levels decreased in plots treated with 

 nitrogen compared with untreated plots. 



Hampton and Scott (1980a) established that a decline 

 in blind seed between 1960 and 1980 in New Zealand 

 correlated with the increased use of nitrogen fertilizer. 

 In field trials, they demonstrated that as nitrogen rate 

 increased, the rate of blind seed infection decreased, a 

 result also reported by Hampton (1987) and de Filippi 

 etal. (1996). 



Under laboratory conditions, Hampton and Scott 

 (1980a) observed that urea directly suppressed apo- 

 thecial formation. However, in field plots. Hampton 

 and Scott ( 1981 ) found no significant differences in 

 number of apothecia among field plots treated with 

 various levels of urea, although a reduction in blind 

 seed infection was observed in urea treatments. They 

 concluded that nitrogen fertilization altered the 

 physiology of the plant, enhancing resistance to G. 

 temulenta (Hampton and Scott 1980b). 



In subsequent studies de Filippi et al. (1996) examined 

 the level of blind seed in adjacent irrigated and 

 nonirrigated field plots to which various rates of urea 

 had been applied. In irrigated field plots, nitrogen 

 application significantly reduced blind seed disease, 

 but this did not occur in nonirrigated plots. As the 

 inoculum source was external to the trial, they con- 

 cluded that plants which are able to utilize available 

 nitrogen develop a greater capacity to resist blind 

 seed. The mechanisms associated with this resistance 

 need to be determined. 



Hampton (1987) reported there was no advantage to a 

 split application of nitrogen (fall, spring) and recom- 

 mended that all nitrogen be applied in spring. Blind 



IX 



