62 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 



required without injury to the fruit, although probably it would be 

 preferable to fumigate a little later in the fall. The purple scale can 

 be found in the egg stage throughout the year. There is, however, 

 a period in the fall during which the smallest proportion of eggs is 

 to be found. With dosages lower than that of eradication the best 

 results can be accomplished at this time, which usually is somewhere 

 about October. The red and yellow scales are born alive and can 

 be successfully destroyed throughout the year. 



In fumigating for any of the scale insects there is one point worthy 

 of consideration. Aside from trying to save the tree from destruc- 

 tion or from having its vitality impaired by the attack of scale pests, 

 the orchardist fumigates principally in order to have his fruit come 

 into the packing house as clean as possible. It would be well, there- 

 fore, to fumigate as nearly as possible at the time which would insure 

 him the cleanest fruit. Although lemons are gathered throughout 

 the entire year, the bulk of the orange crop is taken during the first 

 six months. Thus fumigation during the fall and early winter 

 would be sure to place the cleanest fruit in the packing house. If 

 carried on in the late spring or early summer, such insects as remain 

 undestroyed would have the opportunity to breed throughout a period 

 of several months and infest much fruit. 



The small size of the fruit and to some extent the heat renders 

 fumigation generally unsafe before the month of August. From 

 this time up to December the weather is usually quite dry and not 

 especially cold. December is usually the month during which cold, 

 rainy, and generally unsettled weather may be expected to com- 

 mence and to continue with more or less irregularity into the follow- 

 ing March. Serious injury to the trees may result unless the greatest 

 care is exercised in treating during these winter months. At this 

 period most fruit is almost fully grown, which adds a great weight 

 to the tree. Covering heavily laden trees with fumigation tents not 

 only tears off and scars a considerable amount of fruit, but also 

 breaks off heavy branches. The writer does not believe it advisable 

 to treat trees in such condition. 



The labor question, at all times a perplexing one in fumigation 

 operations, is especially serious where the work is carried on in the 

 winter. The frequent delays, possibly for several days at a time, 

 necessitated by the rainy and damp weather render it difficult to 

 secure good and careful men who will remain continuously with the 

 outfits. As they are paid only for actual work performed, operators 

 earn little more than their living expenses during the irregular hours 

 when work is possible in the winter season. 



After viewing all sides of the question, it is advised that the prefer- 

 able months for general fumigation are from August to December. 

 The treatment can, however, be carried on with both safety and 



