44 MASS. EXPERIMENT STATION BULLETIN 249 



Method of Application 



Thoroughness is the most important factor in the spraying operation. All 

 sides of each fruit should be covered with a film of poison and to do this 

 the tree must be sprayed from the inside as well as the outside. An extension 

 rod equipped with one or two angled nozzles delivering a uniform mist-like 

 spray is the best means of applying the poison, but a spray gun used in- 

 telligently with at least 200 pounds pressure will do effective work on a 

 calm day. On a windy day, spraying should be done only in emergencies, 

 using rods which enable the operator to reach all parts of the tree with the 

 spray. In the spraying experiments extension rods and spray guns were 

 interchanged to fit the weather conditions. Adequate machinery in good 

 repair, and an ample supply of insecticides, fungicides, oil, gasoline, and hose 

 connections should be quickly available to avoid delays and ineffective ap- 

 plication. 



Time of Application. 



Early sprays such as the delayed dormant, pre-pink, and pink are very 

 necessary for combating other pests but give little or no protection against 

 the plum curculio, since the few which are in the trees during these applica- 

 tions feed very sparingly on the buds and leaves. In fact, fruit counts in the 

 experimental orchard in 1926 showed just as good protection where the pink 

 spray was omitted as where it was applied. 



The Calyx Sp^-ay is relatively unimportant in combating the plum cur- 

 culio, nevertheless it is the most important single application (1) in the 

 apple spray schedule in Massachusetts and should never be omitted. At this 

 time from 2 to 5 per cent of the beetles have gone to the trees, and feeding 

 in the developing fruit begins soon after. The later this spray is applied, 

 in the period between petal-fall and the closing of the calyx lobes (usually 

 ten days), the more effective it is against the plum curculio, but it should 

 never be delayed so that it fails to serve its main purpose of filling the calyx 

 cup of the apple with poison. 



The 7-Day Spray {1st Curculio) applied about 7 days after the proper 

 time for the calyx spray is the most effective application against this insect. 

 At this time beetles are actively feeding and laying eggs and the apples are 

 growing rapidly. Individual fruit growers can time this application in their 

 own orchards by spraying as soon as possible after the first punctures are 

 seen. Invariably, however, this will occur about the time the largest of the 

 young apples become 14 inch in diameter. In some seasons frequent heavy 

 rains immediately following this application decrease its effectiveness and 

 make it advisable to repeat the treatment at the first satisfactory opportunity 

 especially on the more suscepible varieties. 



The 3-Wecks Spray (2nd Curcidio) is applied about three weeks after the 

 proper time for the caljrx spray. Under natural conditions the largest num- 

 ber of punctures are made in the fruit about this time. When the number 

 of beetles is small, and previous sprayings have been particularly effective, 

 this application may be less important but it is always advisable. The 

 value of the second curculio spray under certain conditions is well illustrated 

 in Table 16 where the percentage of fi-uit injured was 13 per cent less in the 

 plat to which the 3-weeks application was made than where it was omitted. 



In applying the calsrx, 7-day, and 3-weeks sprays, much benefit will re- 

 sult from timing the applications according to the development of the varie- 

 ties. The young fruit of such varieties as Duchess, Yellow Transparent, and 



