APRICOT DISEASES 



549 



APRICOT DISEASES 



Brown Rot 



Sclerotinia fructigena 

 A decay of the fruit while still on the 

 tree, occurring some seasons in moist 

 localities. The young growth as well as 

 the fruit is also sometimes affected, the 

 new shoots wilting and dying back from 

 the attacks of this fungus. This is the 

 most serious obstacle to stone fruit pro- 

 duction in the Eastern states, but does 

 not find sufficient moisture for its devel- 

 opment in the arid West, except on early 

 varieties In occasional seasons of late 

 rains in the moister localities. 



Spraying with self-boiled lime-sulphur 

 just as the fruit is setting and again with 

 the same following subsequent rains is 

 recommended for trial. 



R.\LPH E. Smith, 



Berkeley. Cal. 

 Bnd Blight 



Characterized by a dying of the buds 

 during the early winter and caused very 

 largely by the fungus responsible for 

 Peach Blight. 



Similar trouble is caused more or less 

 by "Sour Sap" conditions. 



See Blight under Peach. 



Fmit Drop 



The fruit falls to the ground while still 

 very small. Partly due to weather condi- 

 tions and partly to lack of cross pollina- 

 tion, which can be secured by mixing 

 varieties in planting. Seasonal conditions 

 such as heavy rains at blossoming time 

 or frosts may have this effect. The 

 cherry, almond, peach and pear are af- 

 fected in the same way. 



The drop may not occur until the fruit 

 reaches some size. 



See general article on Setti.ng and 

 Droppim; of Fkiits under Fruits. 



PBfiT Spot. See Blight under Peach. 



GuMMosis. See Cherry. 



Scab 



Cladosporium carpoph Hum 

 Same as Peach Scab, which see. 



Blossom Rot 



Sclerotinia 

 The young fruit decays while still very 

 small and enclosed by the calyx or outer 

 cup of the blossom. The trouble occurs 



when wet rainy weather prevails during 

 the time of fruit setting. It commences 

 in a rotting of the calyx cup, which is 

 dead and susceptible to decay by sapro- 

 phytic fungi, which decay spreads to the 

 young fruit. It is caused by various 

 fungi, of which perhaps a species of Scle- 

 rotinia. apparently .s'. Ubertiana. is most 

 common, causing a decay of the young 

 fruit on the tree. When such fruit is 

 picked and placed in moist chamber it 

 develops an abundant cottony mold in 

 which black sclerotia soon forms. This 

 appears to be the same fungus causing 

 the cottony mold or wnite rot of the 

 lemon storage. Botrytis vulgaris is also 

 common in this trouble. Same treatment 

 as brown rot. 



Spraying for shot hole fungus might 

 also be of some benefit in this trouble. 



Shot Hole and Fruit Spot 



Coryneum beijerinckii 

 This fungus is the same as that caus- 

 ing the peach blight and produces in the 

 apricot a spotting of the fruit, shot hole 

 effect in the leaves and killing of the 

 buds. 



Spray with Bordeaux mixture during 

 November and again in spring just as 

 the buds open. 

 See Blight under Peach. 



Sonr Sap and Seasonal Effects 



The apricot is particularly sensitive to 

 sour sap and other seasonal effects. It is 

 a tree having a free flow of sap, quick 

 to respond to stimulating influences and 

 one having the characteristic of all the 

 stone fruits of forming an abundance of 

 gum when injured in any manner. On 

 this account, if any active movement from 

 the roots is .started early in the season by 

 warm weather or an abundance of moist- 

 ure and this activity be checked again by 

 less stimulating weather conditions, 

 trouble is very apt to follow. The sap 

 becomes stagnant in the tissues, full of 

 sugars and other easily fermentable sub- 

 stances, gum begins to form, sunburn 

 may also occur and very often severe in- 

 jury takes place in the tissues of the sap 

 wood and cambium layer. 



Ralph E. Smith, 



Berkeley. Cal. 



