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THE MONTHLY BULLETIN. 



THE MEALY BUG PROBLEM OF GRAPES. 



By Fred K. Howard, County Horticultural Commissioner, Hanford, Cal. 



A packer lifts from the box at her side a beautiful buuch of malagas. To the eye 

 of the casual observer it is a perfect specimen of this variety of grapes, but for 

 some reason, after a hasty glance over them, the cluster is quickly thrown into the 



cull box below. She has detected the clear, crystal 

 globules of honey dew on the berries which indicati-s 

 the presence of an insect which today furnishes one 

 of the big problems of the grape growers of the state, 

 for the insect, the mealy bug (Pseudococcus bakcri) 

 is known to infest grapes in nearly all sections of 

 the San Joaquin Valley, as well as parts of the 

 Sacramento Valley. 



Because fruit that is thus infested cau not be 

 shipped and because drying raisins are more suscepti- 

 ble to smut fungus and dry rot the problem has 

 received considerable attention from growers, packers 

 and investigators. 



It appears that soon after the last moult, the adult 

 females of the mealybug make their way to the 

 maturing grape clusters, settle down and feed on the 

 juicy berries, usually at or near the stem end. Per- 

 haps it is because of the plentiful food supply thai 

 such large quantities of honey dew are exuded, for 

 it takes but a short time for a few insects to give 

 a cluster of grapes a very unappetizing appearance. 

 It is to be regretted that grapes thus infested are often picked and hauled to the 

 packing houses and the insects, being disturbed, will seek out secluded spots in the 

 cracks of the boxes which may or may not belong to the same vineyard and they are 

 thus spread from place to place throughout the district. 



That all boxes returning from packing houses should be fumigated is unquestioned, 

 but the time coming, as it does when each moment counts in quality of product and 

 price received, makes this an important problem for the vineyardist to consider. 



Just what will be the final results of the experiments which Mr. R. L. Nougaret. 

 entomologist for the United States Department of Agriculture, is conducting, it is 

 at present impossible to say. Enough has been done, however, to indicate that the 

 control problem will not be an easy one. 



In the early stages of the experimental work it is clearly shown that control 

 measures of any sort could not be adopted during the growing season, and later work 

 has shown that the only period when successful work could be done is during the first 

 warm spring days before the leaves appear. It is at this time when the greatest 

 number of the young insects, which have wintered over in the egg sacks underneath 

 the old bark of the vines and other secluded places, are to be found feeding on the 

 tender cambium of the spurs which they reach through the cracks in the outer bark, 

 caused by the blunt blade of the pruning shears. At this time a driving spray of 

 the proper material forced into these cracks and crevices, does very good work. 

 Experience has shown, however, that the man doing the spraying must understand 

 the habits of the insects and use this knowledge when applying the spray, for unless 

 the man handling the nozzle directs the spray toward the crevices where the insects 

 are most liable to be found, from almost every angle, the percentage of kill will be 

 very unsatisfactory. 



Control measures are thus made more difficult, for it is practically impossible to 

 get men who have sufficient training to enable them to do this sort of work in a 

 satisfactory manner. With the spraying time limited to not more than two weeks 

 in the spring and with the cost of application almost prohibitive, the problem is 

 made most serious, for spraying seems to be the only logical method of control. 



