6 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 



When a plant becomes encrusted with' the insects, it looks grey in color 

 and upon rubbing the hand along the trunk or branches large flakes of the 

 dead scales become loosened and fall off. The tree looks sick and does 

 not leaf out so early in the spring as a normal tree and usually dies within 

 a season or two. Where there is only a scattering of scale on the plant, 

 it can usually be detected by the sunken places in the bark caused by a lack 

 of food material which has been used by the insect instead of by the tree. 

 Also immediately around the scale the bark takes on a reddish tinge, which 

 is supposed to be caused by a toxin which the insect injects into the plant. 

 This red-like blotch is very characteristic of the San Jose scale, especially 

 on the apple and peach. 



Damage. It is impossible to estimate the amount of damage done by 

 the San Jose scale in Missouri orchards because at present no one knows 

 exactly how extensively Missouri is infested, but it is a known fact that 

 many large commercial and small orchards have been completely destroyed 



Some poorly packed nursery 'stock. This stock was also infested with 

 San Jose scale. It was found and condemned thus preventing its dis- 

 tribution 



by it. However, in the nurseries of Missouri in the past two years, the 

 damage caused by this insect has amounted to the tremendous sum of $20,- 

 OOO.OQ and this is but a drop in the bucket as compared with the damage 

 to the orchards in Missouri. 



Control in the orchard. The San Jose scale can be controlled in the 

 orchards if proper precautions are taken. The most successful method 

 practiced today is the use of lime-sulphur as a dormant spray. Certain of 

 the miscible oils are also used to a greater or less extent with good results. 

 Commercial lime-sulphur can be purchased on the market, which, when 

 mixed with water, one gallon of lime-sulphur to seven gallons of water, 

 makes a most efficient spray. 



A miscible oil makes a good spray when mixed with water at the rate 

 of one gallon of the oil to twelve gallons of water. The lime-sulphur spray 

 is the cheaper spray of the two and is recommended by the United States 

 Department of Agriculture, and by the state experiment stations. 



