PERENNIAL PEACH CANKER 

 ITS CAUSES, DEVELOPMENT AND CONTROL 



George N . Agri os 

 Department of Entomology and Plant Pathology 

 University of Massachusetts 



There is probably no peach orchard in the state that does 

 not have at least some trees whose branches or trunks are infec- 

 ted with the perennial peach canker. In some orchards, however, 

 so many peach trees are infected with cankers and so severe are 

 the infections, that heavy losses in yield and in trees occur 

 annually. And, as it happens with most diseasfs, the orchards 

 with severe infections of peach canker can expect more of the 

 same or even worse losses unless measures are taken to control 

 the disease. 



What is Perennial Peach Canker? 



The perennial peach canker is an area on a peach twig, branch 

 or trunk in which the plant tissues are dead, discolored, col- 

 lapsed and, sometimes, disintegrated. In young cankers, the bark 

 may still be in place, but the tissues underneath are brown, dead 

 and filled with gum. In older cankers, the original bark has usu- 

 ally been broken up and has become disorganized, the tissues under- 

 neath have disintegrated and turned black and the margins of the 

 canker are usually raised by means of rolls of callus tissue pro- 

 duced in the healthy areas surrounding the canker. In the spring, 

 young and old cankers usually exude gum which at first is color- 

 less or amber-colored, but later turns brown. 



Cankers are usually spindle-shaped or ellipsoidal at first 

 and surround a stub, twig or dead limb. Cankers grow much longer 

 up and down the limb than they do laterally on the limb. They 

 may grow several inches in length per year and continue to grow 

 for several years . 



Cankers damage trees by girdling and killing the limbs above 

 the canker, or by so weakening the limbs that they break off under 



the stress of a storm or of the weight 

 weakened by cankers either die or grow 

 pruned off and are lost to production, 

 keep trees sickly and unproductive for 

 later cause the death of the tree. 



of a fruit crop. Limbs 

 so poorly that they are 



Cankers on the trunk may 

 many years and sooner or 



What Causes the Perennial Peach Canker? -_ 



Perennial peach cankers are caused by either one of the two 

 fungi, Yalsa cincta and Valsa leucostoma. The name Cytospora 

 usually reserved for the asexual stage of the fungus, is frequently 

 used instead of Valsa, since the Cytospora stage is by far the one 

 most commonly found in nature. The disease is also known as Valsa 

 canker or Cytospora canker. 



