538 THE MONTHLY BULLETIN. 



THE DATE PALM SCALES AND THEIR CONTROL. 



Bt W. E. WilsiEj County Horticultural Commissioner, El Centro, Cal. 



It is not generally known, but with the introduction of the edible 

 date into this state, there were also introduced two of their enemies, 

 date scales, Parlatoria hlanchardii (Targ.) and Phoenicococcus marlatti 

 (Ckll.). 



Little could be learned about these scales in their native home, only 

 that they were present. What amount of damage was really done by 

 them was for some time, and in a degree still is, a matter of conjecture, 

 but the longer it is studied the more serious it seems to be. No natural 

 enemies have ever been found and it M^as necessary to resort to arti- 

 ficial means to keep them in control. 



In the case of the Parlatona 'blanchardii no remedy was entirely suc- 

 cessful for more than temporary control until after the San Francisco 

 fire, when it was found that ornamental palms withstood the tremen- 

 dous heat and put out new leaves at once after the fire. 



The burning remedy was then tried on the Tempe date garden in 

 Arizona with success and later many trees were entirely cleaned by this 

 treatment. The method being to defoliate the tree completely to the 

 stump, which is burned over with a gasoline torch. 



The Phoenicococcus marlatti has been even more persistent than Blan- 

 chard's scale, for the reason that it works behind and at the base of the 

 leaves, out of sight and out of the light. Little is known of the life his- 

 tory of this scale but it is certain that its work is done upon the vital 

 parts of the plant. Palms, different from ordinary trees and shrubs, 

 grow from the base of the leaf — the whole leaf being pushed out. It is 

 on the tender new growth at the base that this scale, a sucking insect 

 that covers the entire tender surface near the heart of the plant, feeds. 

 The fruit stalks, through which all the nourishment for from a few 

 pounds to as much as seventy-five pounds of fruit must pass, are, when 

 young, exceedingly tender and brittle. Upon these the scale becomes 

 so thick as to cover the entire surface. 



Many remedies have been tried to eradicate this pest without success, 

 for any treatment that was effective on the scale injured or killed the 

 plant. INIany plants were killed by the experiments. The first remedy 

 that has given even a ray of hope was a preparation or solution com- 

 pounded by W. T. Taylor, now of the Sun Drug Company of Los 

 Angeles, for mealy bug. This solution was tried early last spring and 

 different series of experiments were carried on during the summer on 

 both Blanchard's and Marlatt's scales with a degree of success that is 

 almost unbelievable after the experience with other treatments. 



We are now able to kill both scales without injury even to the fruit 

 on the tree. Trees have been treated during the pollinating season and 

 the solution sprayed in large quantities on the fruit just forming with no 

 bad results. 



