6oo 



Bulletin 283, 



III. THE CONTROL OF PLANT DISEASES. 



H. H. WHETZEL. 

 ALFALFA. 

 This disease causes 



Dodder. g^^j^ ^^^^^ ^f ^ifaifa 



Fig. 206. ^Q ^jg_ Around the 



margins of these areas the ground is 

 covered with a tangled mat of yellow 

 threads that twine closely about the 

 plants and kill them. Infested spots 

 should be closely mowed, the stubble 

 sprinkled with kerosene, covered with 

 dry hay and burned. Only seed free 

 from dodder should be used. Samples 

 of seed may be sent to the Geneva 

 Experiment Station to be examined for 

 dodder. Alfalfa seed can be cleaned by 

 sifting through 20x20 mesh sieve made 

 of No. 34 wire. Geneva Bulletin 305. 

 This is the most 



Leaf-spot. serious fungous dis- 



Fig- 207. g^gg q£ ^j^g alfalfa 



crop in the State. It causes the leaves 

 to become spotted and yellow and to 

 fall x^rematurely. New seeding when 

 badly diseased should be topped, but 

 never mowed closely. When older fields 

 are attacked, the hay should be cut a 

 few days early to avoid loss of leaves 

 and to permit a new growth that will 

 usually outgrow the trouble. 



APPLE. 



Commonly known among 



growers as "the fungus." 



Attacks both leaf and 



fruit, usually most evi- 

 fruit. Spray with lime-sul- 

 fur, 1-40 (see table of dilutions p. 500), or 

 with Bordeaux 3-3-50 : first, just before the 

 blossoms open; second, just as the blossoms 

 fall; third, 10 to 14 days after the blossoms 

 fall. In most seasons the second spraying 

 seems to be the most important. Spray 

 thoroughly. For the use of insect poisons 

 with lime-sulfur or Bordeaux mixture, see 



CODLING-MOTH and BUD-MOTH (p. 473). 



This is the same as pear 



Fire-bllght. flight. It usually makes 



ng. 209. itself manifest on the apple 



Fig. 206. Dodder on alfalfa, showing the 

 slender cord-like steins and the bunches 

 of small white flowers. 



Scab. 



Fig. 208. 

 dent on the 



Fio. 807. Alfalfa leaf-spot. 



