seed levels in the study were lowest when all of the 

 spring nitrogen was applied at spikelet initiation. 



In addition to increasing resistance, nitrogen applica- 

 tions can also increase lodging or increase stand 

 density, providing a physical barrier to restrict spore 

 movement up through the canopy (Gorman 1940, 

 Noble and Gray 1945, Blair 1947). 



Stand Density 



Movement of ascospores upward through ryegrass 

 stands is believed to be reduced in a dense canopy, in 

 stands that lodge, or where clover is planted with the 

 ryegrass (Gorman 1940, Noble and Gray 1945, Blair 

 1947). Hampton (1987) reported that as lodging 

 increased, blind seed disease decreased. 



Lynch (1952) and Lithgow and Cottier ( 1953) found 

 no evidence that germination was related to crop 

 density or the extent of bottom growth, although they 

 noticed improved germination in crops that lodged or 

 those with increased percentages of grass in the sward. 

 Wilson et al. (1945) observed that a ryegrass crop 

 which remains standing until harvest was more likely 

 to become infected by G. temulenta than a dense, 

 heavily lodged crop. Noble and Gray ( 1945) found 

 that acidic soils could contribute to poor stands of 

 ryegrass and recommended replacement of ammo- 

 nium sulfate with nitro chalk. 



Fungicide Sprays 



Under field conditions, fungicides applied as foliar or 

 inflorescence sprays were not demonstrated effective 

 in blind seed control by Corkill and Rose (1945), Hair 

 ( 1952), or Hardison ( 1970). However, recent research 

 from the Foundation for Arable Research (Rolston and 

 Falloon 1998) has established that fungicides such as 

 tebuconazole or carbendizim are effective for blind 

 seed control in New Zealand. 



Sprays applied as soil drenches or to the soil surface 

 have been shown effective in reducing the number of 

 apothecia. McGee (1971b) observed that benomyl 

 applied at 2.8 and 5.6 kg/ha reduced apothecia 80 and 

 90 percent, respectively. Hardison ( 1970) eliminated 

 apothecia during April and May with a single applica- 

 tion of benomyl (4.5 kg/ha) applied the previous 

 November, December, or January. Hardison (1972, 

 1975) lists other fungicides effective against G. 

 temulenta under greenhouse conditions. 



Harvest 



Since the primary source of inoculum is the infected 

 seed, early harvest to avoid excessive seed shatter is 

 recommended. Osborn (1947) suggested early harvest 

 under dry conditions as a source of disease-free seed, 

 since late season disease could develop with a change 

 in the weather to wet conditions. In Oregon, there is a 

 narrow window of time in which swathing can occur 

 to avoid seed shatter and obtain optimum seed yields. 



Removal of lightweight or infected seeds during 

 harvest reduces inoculum left in the field. Hardison 

 ( 1949, 1957, 1963) recommends adjusting combines 

 to retain lightweight seeds for removal from fields. 



Straw Residue Removal 



Since dry soil conditions are unfavorable for apoth- 

 ecial development and spore release, Hardison (1949) 

 recommended removing the straw after harvest to 

 allow the soil surface to dry more rapidly in spring. In 

 Oregon, residue is commonly baled and removed from 

 the field. In some cases the straw is finely chopped 

 with specialized flails. Residues that are not suffi- 

 ciently chopped decompose slowly and can interfere 

 with crop growth or development and may leave the 

 soil wet for prolonged periods (Young et al. 1992). 



Postharvest Plowing 



Plowing infested fields reduces the area of infestation 

 by burying much of the inoculum source — the in- 

 fected seeds (Hardison 1963). Hardison (1949) 

 recommended plowing in Oregon before May 1 5 to 

 prevent emergence of apothecia near the time of 

 flowering in ryegrass. The effectiveness of plowing in 

 control of blind seed in Oregon was demonstrated by 

 Hardison (1949. 1957. 1963). 



Crop Rotation 



Blair ( 1947) reported that less infection occurred in 

 stands following 3^4 years of arable crops, suggesting 

 that rotation with crops not susceptible to blind seed 

 may provide a means to reduce inoculum within a 

 field. 



Field Burning 



The effectiveness of field burning in control of blind 

 seed was established by Hardison (1949, 1980). 

 Excellent control of blind seed is achieved with 

 postharvest field burning. For optimal control, the 

 entire dry-straw residue should be open burned. 

 Burning by propane flaming after residue removal 



19 



