1626 



ENCYCLOPEDIA OF PRACTICAL HORTICULTUHE 



rarely in fact, until thoy have blossomod. 

 unless there is a bad attack of blight in 

 a pear or other pome fruit orchard near 

 at hand. There are some cases of young 

 orcliards which I have seen in California 

 and Oregon tliat have blighted somewhat 

 seriously before they had bloomed, but 

 they were alongside badly blighted pear 

 o^chards. The presence of water-sprouts 

 or spurs from the French stock, on whicli 

 pear trees are mostly budded, often deter- 

 mines infection. In many localities tln' 

 entire loss of the pear orchards has come 

 through the infection of water-sjirouts 

 and spurs coming from the crown or 

 roots of the trees. Perhaps 90 per cent 

 of the loss in many of the river orchards 

 in the Sacramento valley has come about 

 through this sort of infection. Right 

 alongside of orchards which have been 

 seriously damaged through the infection 

 of wat9r-si)roiits from the stock or roots 

 we found thrifty trees which were 

 budded on Winter Nelis and Kieffer. 

 These have not gone down with the disease 

 through their ability to resist the blight. 

 It has been particularly noticeable that 

 Winter Nelis is generally quite resistant. 

 Cases have come under my obssrva- 

 tion where the bodies have blighted 

 as far as the union with the Winter Nelis 

 and Kieffer stock and then stopped. If 

 this experience proves universal, it is a 

 strong argument in favor of using the 

 Kieffer and Winter Nelis on which to 

 graft the more tender varieties. These 

 varieties should be worked on Japan 

 roots. 



Several conditions or factors control 

 the spread of the blight after it once 

 enters the tree. Some of these are more 

 or less connected with the conditions 

 favoring infection. The vigor of the tree 

 has a great deal to do with the amount 

 of damage produced after the blight once 

 enters it. Another fact which must be 

 borne In mind is the variety of tree, 

 w^hether apple or pear, or any other pome 

 fruit. All varieties are not equally sus- 

 ceptible under similar conditions, there 

 being in many varieties a certain ten- 

 dency toward immunity. The more vig- 

 orous and thrifty the tree, as a general 



A Bad Infection in tho Body .ind Hoot Sys- 

 tem. Only a small part of the root system 

 li'ft. This tree will continue to bear "fruit. 

 I Original. I 



rule, the more seriously is it attacked by 

 the blight. The vigor itself is the effect 

 of various conditions, such as the fertility 

 of the soil, the amount of manure or of 

 commercial fertilizer used, or kind of 

 cultivation of soil, moisture, rainfall or 

 irrigation, and the jiresence of other dis- 

 eases, such as leaf blight, crown gall, root 

 rot, etc. 



As a rule, trees on rich soil blight more 

 readily than trees which are on poor soil. 

 There are some apparent exceptions to 

 this, and there is a difference in the be- 

 havior of blight on different soils in con- 

 nection with their fertility. Alkali soils 

 seem to favor the blight more than corre- 

 spondingly fertile soils. On the other 

 hand, trees may blight on the acid soils 

 of the Ea.stern states. Stable manure 

 causes the trees to be more susceptible 

 to the blight than those not manured. 

 The age of the tree also exerts an impor- 

 tant influence. The older and slower 

 growing the tree is, the less it is attacked 

 by blight, other things, of course, being 



