188 Pecan-Growing 



rosette in young pecan trees than it is to reclaim old 

 trees that have rosetted for a number of years. For this 

 reason, growers should begin soil improvement with the plant- 

 ing of the orchard and see that the trees are well fed from 

 the start. 



PECAN DIEBACK 



{Botryospceria herengerianay De Not.) 

 Diebaek of pecans has been confused by growers with 

 rosette and also with winter-injury. Matz has show^n, how- 

 ever, that the disease is caused by a specific fungus and is 

 distinct.' He says that ^^ Towards the base of a partly diseased 

 twig, the bark is often of a water-soaked, waxy appearance, 

 and there is usually a definite margin between the infected 

 and healthy tissue. The older diseased portions of the bark 

 or twigs and branches are dry and sunken, the longitudinal 

 ruptures in these being more conspicuous, and bear the fruit- 

 ing bodies of the fungus which are embedded in a black 

 matrix or stroma. Numerous young shoots often start out 

 further back on the branches which have been partly killed. 

 As the disease spreads these young shoots may become in- 

 fected and ultimately die. These dead clusters of short 

 branches suggest a similar symptom commonly observed in 

 rosette. However, this, as in rosette, is a physiological re- 

 action. No deformity or crumpling of leaves is found to be 

 due directly to diebaek, though it may be associated with it 

 through some other cause.'' 



Control, 



Pruning out and burning all dead wood of pecan trees 

 infected with the diebaek disease is the means of control 



^ J. Matz, Bull. 147, Fla. Exp. Sta., pp. 142-143. 



