For example, ARS scientists and their collaborators recently solved 

 a cultural problem that is common to Oregon, and which may occur in 

 other seed -producing States. The problem was infestations of hairy vetch 

 in crimson clover being grown for seed. Seed of hairy vetch and crimson 

 clover germinate at practically the same time, but vetch grows more 

 rapidly and soon forms a canopy that covers the clover. The canopy causes 

 the clover to lodge and reduces the yield of harvestable seed. When crim- 

 son clover is ready for harvest, hairy vetch is still green and causes 

 threshing difficulties because it tangles and contains too much moisture. 



The scientists found that spraying the rapidly growing vetch plants 

 when their shoots were 10 to 12 inches long with 1/4 pound of MCPA 

 (2 -methyl-4-chlorophenoxyacetic acid) in 40 gallons of water per acre 

 successfully controlled the vetch. At that tinne, crimson clover is 3 to 4 

 inches high. The treatment injures the clover temporarily, but it recovers 

 to produce a normal crop of seed. 



HARVESTING CROPS THAT SHATTER SEED IN THE FLORET 



Crimson clover, subterranean clover (subclover), alta fescue, the les - 

 pedezas, and many other crops fall into this category. Although suction 

 seed reclaimers (see page 9) can be used to reclaim their shattered seed 

 taking the seed directly from the plant usually results in higher quality 

 seed and fewer postharvest cleaning problems. Consequently, the techniques 

 discussed below are primarily aimed at harvesting this type of crop before 

 shattering becomes excessive. 



Time-of-Harvest Recommendations 



Early as possible harvests are recommended in the Southeast because 

 rain at harvesttime, especially during spring harvest, is always an immi- 

 nent hazard can shatter 30 percent or more of a mature crop. But 

 several "ifs" govern the selection of a harvest date that is early enough 

 but not premature: 



1. If the field can be harvested in 1 day, and if the crop ripens uni- 

 formly, direct combining should begin when 5 to 1 percent of the seed are 

 still immature. 



2. If the crop ripens uniformly, and if 2 to 3 weeks are needed to 

 combine, direct combining should begin when 15 to 20 percent of the seed 

 are immature. 



Twenty percent immaturity is the maximum allowable. Combining 

 when more than 20 percent of the seed are immature usually results in 

 low yields, high combine losses (especially in crimson clover), low ger- 

 mination, and too much seed nnoisture, which could cause heating in stor- 

 age. If the unharvested seed become extremely dry, however, excessive 

 seed injury can occur during late harvests. 



