of nitrogen is particularly important for plant height and hence, straw quality and yield. When the prior-year crop was a legume, or where ample manure is applied, nitrogen rates can be reduced somewhat. Weed control The vigorous growth of oats tends to choke out most weeds. A few tall broadleaf weeds, such as ragweed, goosegrass, wild mustard, and buttonweed (velvetleaf), occasionally create a problem, as they complicate harvest and reduce yields. These can be controlled with a modest application of a broadleaf herbicide, such as 2,4-D, while the weeds are still small. Pests and diseases Oats are relatively free from diseases and pests. Nonetheless, it does suffer from some leaf diseases, such as Leaf Rust, Stem Rust (Puccinia graminis f. sp. avenae), and Crown Rust (P. coronata var. avenae).. Crown rust infection can greatly reduce photosynthesis and overall physiological activities of oat leaves, thereby reducing growth and crop yield. A few lepidopteran caterpillars feed on the plants—e.g. rustic shoulder-knot and setaceous Hebrew character moths, but these rarely become a major pest. Harvesting Harvest techniques are a matter of available equipment, local tradition, and priorities. Farmers seeking the highest yield from their crops time their harvest so the kernels have reached 35% moisture, or when the greenest kernels are just turning cream-colour. They then harvest by swathing, cutting the plants at about above ground, and putting the swathed plants into windrows with the grain all oriented the same way. They leave the windrows to dry in the sun for several days before combining them using a pickup header. Finally, they bale the straw. Oats can also be left standing until completely ripe and then combined with a grain head. This causes greater field losses as the grain falls from the heads, and to harvesting losses, as the grain is threshed out by the reel. Without a draper head, there is also more damage to the straw, since it is not properly oriented as it enters the combine's throat. Overall yield loss is 10–15% compared to proper swathing. Historical harvest methods involved cutting with a scythe or sickle, and threshing under the feet of cattle. Late 19th- and early 20th-century harvesting was performed using a binder. Oats were gathered into shocks, and then collected and run through a stationary threshing machine. Storage After combining, the oats are transported to the farmyard using a grain truck, semi, or road train, where they are