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The camphor Scale Situation

1925; Oxford University Press; Volume: 18; Issue: 3 Linguagem: Inglês

10.1093/jee/18.3.473

1938-291X

H. K. Plank,

Yeasts and Rust Fungi Studies

The camphor scale,Pseudaollidia duplex(Ckll.),was first recognized as a pest in the United States in 1920, when it was found severely infesting camphor-tree, common camellia, sweet olive, and a number of other plants in New Orleans. It was doubtlessly introduced directly from Japan at this point and at Mobile, Alabama, and Alvin, Texas, on ornamental and citrus nursery stock. It has also been seen a number of times elsewhere on plants consigned for entry into the United States from Japan. This scale has been found on approximately 150 different species of plants in numerous places in Alabama, Mississippi, Louisiana, and Texas; but it has now been eradicated in Mississippi. Of these hosts, camphor-tree, Japanese persimmon, sweet olive, common camellia, Satsuma orange, rose, Japanese honeysuckle, common fig, confederate jasmine, and glossy privet seem to be the most preferred. While the susceptibility of the different hosts is quite variable, the scale seems to cause the most injury to Japanese persimmon, camphor-tree, sweet olive, Satsuma orange, common camellia, certain roses, and Japanese honeysuckle, all of which are seriously disfigured, or partiaIly killed, by prolonged attack. The presence of the camphor scale in the Alabama citrus district makes it very important from a commercial standpoint. Here it ranks with the purple scale in its ability to spot the fruits about the time they ripen and thus to reduce considerably their market value. The camphor scale seems to be well controlled by most oil sprays. It is recommended that all heavily infested trees except citrus and very tender plants be pruned and then sprayed once in the fall and again in the early spring with a heavy lubricating oil emulsion so diluted as to contain 2% of oil. Citrus and other tender plants in some of the Gulf states should receive the same treatment but light lubricating oil emulsion should be used, so as to avoid as much as possible the risk of spray injury. Two additional “summer” applications are sometimes recommended using 1% heavy oil emulsion for the more resistant plants and 1% light oil emulsion for stich as citrus and other tender plants. The first of these applications should be made about May 15 and the second about July 30 to control the immature scales of the first and second broods, respectively. If fumigation with hydrocyanic acid gas is employed, ¾ oz. av. of sodium cyanide in 2½ fl. oz. of water and 1⅛ fl. oz. of sulphuric acid should be used for each 1000 cu. ft. of space at an exposure of 1 hour when the temperature is 80°F. or above. When the temperature is below 80°F., 1 oz. av. of sodium cyanide in 3 fl. oz. water and 1½ fl. oz. of sulphuric acid should be used for this space at the same exposure.