1620 



ENCYCLOPEDIA OP PRACTICAL HORTICULTUHE 



above statements are iiiade in ordi'r that 

 all districts which are still free from 

 blight will make a hard fight to keep it 

 out. There is every reason to fear blight 

 and to fear it all the time. 



There is a common impression among 

 some of the older residents of the Rogue 

 River valley that pear blight existed in 

 tha valley eighteen years or more ago. 

 .\n unpublished "History of Pear Blight 

 ill Rogue River Valley" is one of the best 

 lii.storical evidences that the blight did 

 not exist so long ago. The statements 

 that certain varieties of pears which are 

 known to be practically immune were 

 badly affected and those very susceptible 

 to the disease remaining untouched, even 

 though alongside the blighted varieties. 

 is proof positive that the trouble was 

 really something else. Furthermore, the 

 quince and the Spitzenburg apple were 

 not noted as having been attacked at all. 

 Again, several orchards in which it was 

 said that blight occurred eighteen years 

 ago, had not come into bloom at that 

 time. It Is very rare that blight is 

 troublesome before the trees come into 

 bloom, and the reason for this we will 

 show later on. The explanation which 

 seems best to fit what many of the old 

 settlers thought to be blight is that un- 

 favorable soil and weather conditions 

 was the real cause of the trouble. We 

 know that undrained soils, especially if 

 they are cold, have a bad effect on many 

 varieties of trees, especially apples and 

 some varieties of pears. The common 

 term, "sour sap," is certainly the trouble 

 they had in mind and not blight. 



Pear blight did not infest the orchards 

 of the Rogue River valley until the spring 

 and summer of 1907. As a matter of fact, 

 the real outbreaks were not found until 

 past mid-summer. We know that this 

 is true by our knowledge of the blight 

 conditions in the upper Sacramento River 

 valley. Beginning with the fall of 1907, 

 when the writer first saw the Rogue River 

 valley, up to the present time, the loss in 

 the commercial pear and apple orchards 

 has been comparatively small. 



Host Plants 



'I'he disease is usually most serious on 

 the pear. It attacks the apple, however, 

 to a very serious extent, sometimes disas- 

 trously, as I have already note'l. The 

 quince, wild crabapple, various species of 

 the hawthorn, the service berry, mountain 

 ash and other wild fruits belonging to the 

 pome tamily are more or less subject to 

 its attacks. The loquat, which is a rela- 

 tive of the pome fruits, is a somewhat 

 peculiar host for this disease. Some va- 

 rieties of plums and the apricot are at- 

 tacked in a small way by blight, but from 

 a practical point of view the injury is 

 not serious enough to attract attention. 

 Wherever native shrubs or trees of the 

 pome species are abundant in the neigh- 

 borhood of pear and apple orchards, at- 

 tention should be given them, and it 

 would be better that they were destroyed. 

 There is this much to say, however, the 

 native shrubs do not, as a rule, tend to 

 hold the blight over as do the cultivated 

 orchards. 



Appearance 



The blight usually attracts attention in 

 the spring of the year, and a month or 

 so after the blossoming period. It is then 

 found that the flower clusters are shrivel- 

 ing and dying; however, if examination 

 has been made very carefully the blight- 

 ed blossoms may be seen to have been in- 

 fected for some weeks previous to this 

 time. The twigs will also be found to 

 be dying. In some cases the new shoots 

 are seen to be attacked at the tip and 

 the disease running downward, killing 

 the tender twigs, completely and running 

 down the bark of the twigs and branches 

 in the form of an ooze, which is slimy in 

 apiiearance and somewhat sweetish to the 

 taste. Usually blossom blight accounts 

 for the greater part of the infection 

 points, but in some cases twig infection 

 exceeds blossom infection. If the season 

 is favorable and the other conditions are 

 just right, the disease may not run 

 further than a few inches. It may kill 

 only the blossom clusters or the fruit 

 spur a few inches down the twig and 

 then stop. On the other hand, if condi- 

 tions are very favorable for the tree. 



