April, '21] 



headlee: dusting for insect control 



215 



delivering the same materials used for dust in a water suspension was 

 carried out in New Jersey fully only the first year. 



An experiment on apple and another on peach was undertaken at 

 Glassboro and still another on peach at Vineland. The difference be- 

 tween the experiments at Glassboro and at Vineland lay in the fact 

 that at Glassboro an effort was made to maintain a coating of the dust 

 throughout the period of insect attack, while at Vineland no more appli- 

 cations of dust were made than were made of liquid spray. On peach 

 both at Glassboro and at Vineland excellent control of both diseases 

 and insects was obtained, but the foliage in both instances was so 

 severely burned that the fruit never reached a satisfactory size. 



In 1914 tests were again undertaken on peach at Vineland and on apple 

 at Cranbur}^ Again the control obtained by dust on peach at Vineland 

 was excellent, but the damage done to the foliage was so severe as to 

 prevent the fruit from reaching proper size for market. 



By 1917 a corrective for foliage injury, due to this dust mixture, had 

 been found in the form of hydrated lime. The Horticultural Depart- 

 ment of the Station undertook an extensive test of the relative value of 

 sulfo-arsenical lime dusts and self-boiled lime sulfur-arsenate of lead 

 liquid sprays. The control of insects and diseases obtained in all three 

 years of experiments and the freedom from injury found in 1917 was such 

 as to make the New Jersey Station feel that further tests of this material 

 upon peach were unnecessary. The sulfo-arsenical lime dusts have been 

 recomjnended since that year as practically equivalent in efficiency to 

 the self-boiled lime sulfur arsenate of lead liquid sprays. 



The data relative to the efficiency of the sulfo-arsenical lime dusts 

 as compared with the liquid treatments on peach are set forth in the 

 following table : 



On apple the results have been very different from those on peach and. 

 the New Jersey Station has not ever and is not now ready to recommend 

 the sulfo-arsenical dusts as in any way equivalent to the liquid sprays 

 in efficiency in control of insects injurious to that crop. 



In 1919 the New Jersey Station undertook a set of experiments in an 

 orchard very severely infested with codling moth and curculio. The 

 blocks were laid out by the Acting Horticulturist and the Entomologist. 

 The materials were applied by the orchardist with his own organization 



