PEACH GROWING 13 



The most important control measure is spraying or dusting with sulfur. Since 

 brown rot is apt to develop late in the season, particularly during periods of high 

 temperature and rain or high humidity, late sprays or dusts may be needed. 

 Sulfur dust applied just before harvest is very helpful in preventing the develop- 

 ment of rot in the harvested fruit. See Spray Program. 



Peach Scab is another fungus disease which attacks fruit, twigs, and leaves. 

 It is most noticeable as small olive-black specks on the fruit. However, it often 

 causes circular brown spots on the leaves and twigs as well. The fruit spots may 

 enlarge and coalesce, forming large, irregular, sooty-looking areas which usually 

 develop large cracks. It is through these cracks that much of the brown rot of 

 the fruit develops. Peach scab can be controlled easily by timely spraying or 

 dusting with sulfur. See Spray Program. 



X-Disease or Yellow-Red Virosis of the peach is a virus disease which can be 

 transmitted by budding, but is also spread by other means which are not known. 

 X-disease is always associated with diseased chokecherrics located near by. 



The leaves of chokecherrics infected with X-disease are intensely colored, light 

 green, greenish yellow, or reddish yellow to flaming red. The tissues along the 

 midrib and veins are the last to lose their green color so the leaves may have a 

 mottled appearance. Leaves may be normal in size or small and "mouse-eared." 

 The tip leaves usually lose their color last, leaving rosettes of green among the 

 bright reds and yellows. 



Diseased peach trees appeal nearly normal during the spring and early summer. 

 About mid-June small, yellowish or yellowish-brown spots appear on the leaves 

 on one or more branches. The leaves turn yellowish and the spots fall out giving 

 a tattered appearance (Figure 6). Diseased leaves become twisted and curled 

 toward the midrib. Finally, the leaves may drop. On badly diseased branches 

 all leaves may fall off except a few at the tips of the shoots (Figure 6). The 

 fruits usually drop from such badly diseased trees around midseason or earlier. 

 If they remain on the tree, they are small and bitter. 



X-disease spreads rapidly from chokecherry to peach, but much less extensively 

 or not at all from peach to peach. It can be controlled by killing all chokecherrics 

 around the site before a new orchard is planted, by securing nursery stock from 

 areas free from the disease, b}' avoiding buds from diseased orchards when prop- 

 agating, and by killing all chokecherrics in the vicinity of established orchards. 

 Removing diseased peach trees front young orchards probabh' helps, but removing 

 them from bearing orchards is of doubtful value. 



Chokecherrics should be eliminated for a distance of at least 200 feet from the 

 orchard, but .500 feet is better. It is especially important to kill all choke cherries 

 around the site before planting a new peach orchard. 



Chokecherrics can be killed by spraying with a weed killer, such as ammonium 

 sulfamate or a proprietary mixture of sodium chlorate and a deflagration agent. 

 These are used dissolved in water at the rate of % pound per gallon. Spraying 

 may be done at any time when the trees are in leaf, but probably is most effective 

 In early July. The leaves should be thoroughly wetted with the spray. High 

 pressure is not necessary. Since these materials kill by penetrating the leaves 

 and then being carried down to the roots, the trees should not be cut till the year 

 after spraying. Trying to kill chokecherrics by cutting, pulling, or digging is a 

 waste of time for any pieces of root left will sprout. 



