MICHIGAN ACADEMY OF SCIENCE. 185 



colonies are at first cnnii»osed of nnuli branched, hyalin, septate 

 mycelium. These colonies become dark brown in the center on the 

 ai){>earance of spores, whicli are formed in foiir days. 



Tests of Fiiiif/iciths (HI ilir Altcnidi id. Michijian ^rown Northern 

 Spy apples from an orcliard that had been thoronj»hIy sprayed with 

 lime-sulfur, as shown by the entire absence of scab, were found 

 to contain in one barrel about 25 per cent of fruit infected with this 

 Alternaria. 



The question was thus brou<>ht up as to the effect of lime-sulfur 

 when directed against this organism and accordingly the following 

 tests were made with various sprays. 



Method of Testing the Fungicides. The method was the slide 

 germination test developed by Reddick and used by Walhice and 

 Blodgett in their work with lime-sulfur. Slides were S])rayed with 

 the fungicides to be tested, one-half of the slide being left bare to 

 serve as a check. The slides Avere dried under atmospheric condi- 

 tions to allow for any chemical changes which might result from 

 atmospheric activity. A water suspension of spores was made up 

 containing sufficient number to give a satisfactory count in each 

 drop. From three to ten slides of each strentgh were made and five 

 fields were counted in each drop, to obtain the percentage of spore 

 germination. 



The slides were sprayed with a hand atomizer which produced a 

 fine spray, care being taken not to let the drops run together, thus 

 reproducing field conditions as closely as possible. 



The viability of spores was very high, the checks averaging almost 

 100 per cent germination. 



Lime-Sulfur Tests. A concentrated lime-sulfur Avas used testing 

 32 degrees Baume and various dilutions were tried. This was re- 

 peated with the addition of lead arsenate at the rate of 2 lbs. to 

 50 gal. of water. 



PERCKXTAfJE OF SPOKE GERMINATION ON SPRAYED SLIDES. 



Strengths 1-10 1-20 1-30 1-40 1-50 1-100 



Lime-sulfur. 25% 45% 64% 81% &5% 98% 

 Lead arsenate 



added 12% 18%^ 38% 42% 43% 88% ■ 



From the above results it is concluded that lime-sulfur will 

 not prove effective in controlling this fungus with any strength 

 which could be used on the foliage with safety. The ordinary 

 strength of 1-40 killed only 1!)^; of the spores. Llence it i.s pos.-<ible 



