672 Grasses and Leguminous Crops in [N'ew York 



Red-spoi or hllglit 

 This disease is characterized by somewhat circular or elongated 

 red spots on the leaves and leaf sheaths. These spots appear 

 much like rust spots to the ordinary observer and when abundant 

 the affected leaf dies prematurely. This disease is most prevalent 

 in humid regions and is especially destructive to Sudan grass. 

 Selection of resistant varieties is the only method of control known 

 at the present time. 



INSECT PESTS 



The most important insect pests of sorghum are the sorghum 

 midge, the chinch bug, the grasshopper, and the fall army worm. 



Sorghum midge 



This minute reddish fly lays its eggs in the sorghum flower when 

 it is in bloom and the young larvae feed on the juices of the 

 developing ovary, thus preventing the formation of the seed. The 

 sorghum midge is abundant only in the warm, humid portion of 

 the United- States from Texas east to Florida. In this section it 

 renders the production of profitable seed crops very nearly impos- 

 sible. Very early or very late planting, thus causing the sorghum 

 to reach the blossoming stage at a time when the midge is not 

 abundant, are the most practical ways known to escape the ravages 

 of this insect. 



Chinch hug 



These bugs, when abundant, do considerable damage to young 

 sorghum plants. They are especially fond of milo and often leave 

 kafir and the sweet sorghums almost untouched while they devour 

 an adjacent field of milo. The methods used to prevent attacks 

 of chinch bugs on the small grains can be u'sed to protect the sor- 

 ghum crop.* 



* The rhinch bug, only about oiip-fifth of an inch long, stout, black and with 

 white wings, is one of trio most serious ins?ct enemi(>s of grasses, small grains, and 

 corn in the Central States, especiall.v in the somewhat dry climate of Kansas. It 

 produces two generations annually, the second frequently invading adjacent culti- 

 vated fields and attacking sorghum as well as corn and other grains in August or 

 September. Injury by this pest in New York State is occasional and confined 

 largely to timothy meadows, this being especially true in the St. Lawrence and 

 upper Hudson valleys. The bugs may become so abundant as practically to destroy 

 the timothy late in the season, and portions of fields producing heavy crops one 

 summer may be almost barren the next. 



Slow burning when the vegetation is dry will destroy most of the hibernating 

 hugs at the base of the grasses and is advisable for roadsides and fence-side thickets.. 

 Burning of timothy meadows is not recommended because there is danger of injur- 

 ing the grass. A moderately frequent rotation will do much to keep the pest from 

 becoming excessively abundant. Chinch bugs spread by crawling to nearby fi(>lds, 

 and consequently some care may well be exercised not to plant near grassy land 

 those crops likely to be injured, as such land is frequently badly infested with this 

 pest. However, "it is not difficult to protect fields from invasion by the use of bar- 

 riers, such as dusty furrows, trips of tar, or similar jjevices. — Dr. E. P. Felt, New 

 York State Entomologist. 



