34 Report of State Board of Horticulture. 



for market. It will be a reflection on the intelligence and 

 energy of any fruit-grower of this Valley if he falls to smudge 

 for frost next spring, should the necessity require it. 



PEAK BLIGHT. 



This is a germ or bacterial disease of the pear, apple, and 

 quince. Professor O'Gara says it affects the wild crab apple, 

 haw and serviceberry, A little more than two years ago this 

 disease aDpeared among some of the apple and pear trees 

 of the Valley. When it first appeared none of our growers 

 had any knowledge of a practical nature as to its treatment. 

 Many fake remedies and suggestions as to Controlling it were 

 scattered among the fruit-growers, and not until Professor P. 

 J. O'Gara, government expert on pear-blight, was assigned 

 to this district to aid the growers was any progress made in 

 Controlling the diesase. Pear blight in its worst stage was 

 called "sour sap" by growers who were without knowledge 

 , as to its origin, and their remedy to relieve the "sour sap" 

 they supposed was the matter of their trees only spread the 

 germs of the disease, and caused increased infection of 

 healthy wood. About fifteen hundred trees that were in bear- 

 ing were lost from pear-blight in the Rogue River Valley for 

 want of scientific knowledsfe as to what the disease was, and 

 its method of treatment. Professor O'Gara taught our grow- 

 ers how to treat the disease with success, and how to identify 

 it. Now we are having gratifying success in Controlling it 

 by cutting out the parts of the tree that are infected with the 

 germs. 



There are but two ways for a healthy tree to become dis- 

 eased with the germs. One through the blossom, and the 

 other where an abrasion is caused by careless cultivation. 



In all cases where pear-blight exists in an orchard the 

 source of annual infection is from hold-over blight that be- 

 comes established in the larger sappy limbs. The germ, to 

 live through the winter, must have ample moisture, and the 

 larger limbs furnish this moisture. For want of moisture, 

 many germs perish in the smaller limbs, but hold-over is sure 

 to be found in the spring if not sooner discovered and cut 

 out. As the tree becomes dormant in the fall and sap ceases 

 to be active, the germs in a hold-over case also become dor- 

 mant, and do not multiply rapidly. With the first warm days 

 of spring the sap becomes active, the heat of the sun warms 

 up the hold-over, and the diseased tissue of the hold-over fer- 

 ments, and the fermented sap exudes, carrying millions of 

 germs. The bees and other insects feed on this diseased flow 

 from the hold-over, fly to a pear or apple bloom, and infest 



