March, 1934] Agricultural Research in N. H. 21 



Results on Apple-Scab Sprays Repeated 



Results with apple-scab sprays continue to show that 200, 300, and 

 400-pound pressures give substantially the same degree of control. 

 This, the investigator, 0. Butler, points out, need cause no surprise 

 since coverage is the important thing and not the pressure with which 

 the coverage is obtained. Another finding is that night spraying gave 

 as satisfactory control as day spraying. {Hatch Fund) 



Crop Size and Harvest Date Influence Bitter-Pit 



Evidence continues to pile up, showing that the fertilizer treatment 

 of the orchard has little if any effect on the development of bitter-pit 

 in apples, but that the size of the crop and the elate of harvest do 

 influence the amount of infection. 



0. Butler found that fruit picked after October 15 exhibited less than 

 30 per cent bitter-pit infection after several months storage, while fruit 

 picked previous to that date developed nearly 50 per cent infection. 

 The fruit selected for the storage test was free from evidence of the 

 malady, but was harvested from trees in which the disease had de- 

 veloped. {Purnell Fund) 



Tests of Weed Killing Chemicals 



Comparative trials with sodium chlorate and ammonium thiocyan- 

 ate as weed killers showed both to be equally strong, but the sodium 

 chlorate poisons the soil for all plants for a long period of time, while 

 the ammonium thiocyanate soon proves stimulating to new groAvth. 



Both herbicides were applied as sprays in field control of yellow 

 hawkweed, the chlorate in amounts equivalent to 100, 200 and 400 

 pounds per acre and the thiocyanate at the rate of 50, 100, 200, 400 

 and 800 pounds per acre. When more than one spray was used the 

 inteiwal between applications was approximately 25 days. More than 

 two sprays were seldom needed. 



On a weight basis the herbicides proved equally toxic, although the 

 chlorate seemed somewhat less active in the latter half of the season 

 while the thiocyanate remained equally toxic throughout. 



In checking on the persistency of toxicity, four crops of wheat were 

 grown in pots over a period of 210 days, the chlorate having previously 

 been applied in amounts equivalent to 100, 200, 400 and 800 pounds 

 per acre. When the last crop was harvested only the plants in pots 

 which had received the smallest application of the herbicide were 

 found to have grown normally. 



Three successive crops were grown in soil treated with the thiocyan- 

 ate, and the second crop showed stimulation regardless of the amount 

 of the herbicide that had been used. 



Sixty-three days after the herbicides were applied, ammonium thio- 

 cyanate used at the rate of 800 pounds per acre was stimulating 

 gro^iih, while sodium chlorate at only 100 pounds per acre was still 

 toxic. {State Fund) 



