348 



STATE HORTICULTURAL SOCIETY. 



It is widespread and very serious some years; other years it is but little prevalent. 

 This disease has also been more troublesome in California. It is due to a fungus 

 which may be held in checli by spraying, as appears clearly from recent experi- 

 ments in California by Newton B. Pierce. The peach cercospora has also given 

 some trouble in California. A fungous trouble liuown as black spot (fig. 8) often 

 leads to cracliing of the fruit and subsequent rot, especially in rainy periods. This 

 is most prevalent on late varieties. Rot is one of the most serious troubles that 

 visit the grower. The disease is due to a fungus, and in wet, hot weather, it 

 spreads with great rapidity from fruit to fruit, and even attaclvs the peaches in 

 baskets on the way to market and while on the fruit stands. It is a disease that 

 winters over in the rotted fruits of the previous year 

 which either remain hanging on the tree or have fallen 

 to the ground, and is to be combatted by carefully 

 removing and burning all affected fruit. If this is not 

 done systematically the crop may be destroyed even 

 before it is out of blossom. Spraying with copper 

 fungicides has been recommended for this disease, but 

 as yet the evidence in tlieir favor is not entirely con- 

 clusive. Sulphur dust blown into the trees during the 

 prevalence of the rot has also been recommended and 

 appears to have some value. A safe, efficient powder 

 or spray for prevention of this disease would be 

 invaluable. 



Crown galls or root galls are irregular tumors on the 

 trunk and roots. These are often of large size and 

 occur most frequently at the junction of the root and 

 stem. This disease occurs in many parts of the 

 United States, in nurseries as well as in orchards, 



and is seriously prevalent in parts of New Jersey, Texas, and California. No rem- 

 edy is known, and even the cause is yet to be determined. Many growers think the 



Fig. 16.— Black peach aphis 

 (Aphis persiccc niger), the 

 common, wingless, vivi- 

 parous form. (Slingerland 



Fig. 17.— Black peach aphis (Aphis persicce niger), viviparous, winged form. (J. B. Smith.) 



disease is communicable, and in planting orchards it is safe to reject all trees show- 

 ing any signs of it. 



The root knot, which should be carefully distinguished from the preceding, is 

 a disease caused by a small "eel worm" or nematode. The knots (fig. 9) due to this 

 cause are generally much smaller than the preceding, and on miscroscopic exami- 

 nation of fresh knots it is usually not difficult to find cavities containing the eel 

 worm in various stages of development. This nematode attacks the roots of a 

 great variety of plants and is quite troublesome to the peach in parts of Georgia, 



