262 PLANT DISEASES 



In no case should the temperature go above 129° or below 124° F. 

 This treatment will also be effective for covered smut. 

 Oats. Loose Smuts ( Ustilago avencB and Ustilago levis). — Both 

 characteristic loose smuts, and both seedling infection. 



Control. — Formalin treatment, as indicated above. 

 Whe.\t. Stinking Smut or Bunt {Tilletia foetens). — Can be de- 

 tected in the field by the flaring of the beards, in the bin by the 

 peculiar fetid odor and by breaking open the kernels. The 

 seed coat remains intact. Seedling infection. 



Control. — Formalin treatment, as above. 

 Loose Smut {Ustilago tritici). — Characteristic loose smut of the 

 head appearing at blossoming time. Flower infection. 



Control. — Hot water, as indicated above. The temperature 

 of tub 2 should be 129° F., and the seed should be left in ten 

 minutes. If the temperature of tub 2 should go above 129° or 

 fall below 126° the length of treatment should be diminished or 

 increased accordingly. In no case should the temperature go 

 above 131° or l)elow 124° F. 

 Storage rots (Penicillium e.xpansum and P. italicum). — These two 

 organisms are responsible for much of the rot appearing in storage 

 or transportation. The former is the common one on apples, the 

 latter on oranges and lemons. These organisms are not able to 

 enter through an unbroken surface, but are dependent upon 

 cracks, bruises, scab spots, etc. 



Control. — Avoid puncturing the skins with shears or finger- 

 nails, handle and pack with care to prevent bruises, and spray to 

 prevent scab spots. Store at a temperature of 32°. In making 

 long distance shipments, pre-cool the car and ship under ice. 



Diseases of different Plants or Crops 



Alfalfa. Leaf Spot (Pseiidopeziza medicagiais). — Small black spots 

 on the leaves. Causes the leaves to turn yellow and fall. 



Control. — Frequent close mowing usually holds the disease 



in check. 



Dodder (Cuscuta epithjmum). — A tangled mat of yellow threads 



entwining the alfalfa stems. Usually appears in spots in the 



field and spreads from these points. Is easily spread by the rake, 



