116 Maine Agricultural Experiment Station. 1918. 



Discussion of Results. 



As has already been pointed out, the weather conditions 

 both years, particularly during the early part of the season when 

 infection occurs and the distribution of scab is most rapid, were 

 exceedingly favorable for the development of the disease. The 

 fact that nearly 39 per cent of the fruit on the unsprayed check 

 plot in 191 6 and over 98 per cent in 191 7 were classed as scabby 

 indicates that both seasons, particularly the last, provided con- 

 ditions for a rigorous test of the spray mixtures used. The 

 orchards were plowed early in May 1916, thus turning under 

 the leaves of the previous season, except those that lay near the 

 bases of the trees, before the ascospores of the fungus had de- 

 veloped. This undoubtedly materially reduced the possibilities 

 of primary scab infection that spring. General observations 

 indicated that scab developed with greater severity on unplowed 

 and unsprayed orchards near by than it did on the unsprayed 

 check plot, but no accurate data were obtained on this point. 



It will be noted that during the first season under discussion 

 every spray material used showed marked and some of them 

 excellent scab control. On the other hand, the efficiency of 

 the same materials in 1917 was exceedingly low. In the light 

 of past experimental spraying work in the same orchard it is 

 believed that the very abnormal weather conditions during the 

 early part of the season, which materially delayed the first two 

 applications, are primarily responsible for the poor results ob- 

 tained the second season. Undoubtedly in practical work an ad- 

 ditional, earlier application of a fungicidal spray when the leaves 

 are about one-fourth inch in diameter, such as has been recom- 

 mended by Brittain and Sanders as the result of their work in 

 Nova Scotia, would be very .effective in Maine under such con- 

 ditions as these. This will be discussed farther under the topic, 

 "The importance of the blossom bud application." 



FRUIT RUSSETING OX THE PLOTS AS A WHOLE. 



Much of the following discussion with reference to the 

 desirable and undesirable qualities of certain spray combina- 

 tions with regard to russeting would not apply in the same 

 degree to a number of commercial varieties of apples. Atten- 

 tion is again called to the fact that the skin of the fruit used 



