What is in this article?:
- This past winter, as was the case the two previous winters, juvenile pistachio trees demonstrated considerable blackening of the trunk, gumming, early leaf-out and dieback in a number of orchards in the southern San Joaquin Valley.
Additional observations of WJTD
Additional observations of WJTD are as follows:
a) trees go into dormancy apparently vigorous and healthy;
b) topographically low-elevation orchards have most, but by no means all, of the WJTD, but damaged trees are often not in the lowest areas of a given orchard;
c) rootstock starch concentrations are much higher during early spring at leaf out in WJTD trees than in unaffected trees;
d) high sodium levels in the soil and water, and soil characteristics such as presence of hardpans, appear to increase WJTD;
e) sodium concentration is highly elevated, when measured in mid-May, in the scion and rootstock bark of WJTD-severely affected trees growing in salt-impacted soils;
f) the scion is usually more adversely affected than the rootstock, but the entire tree may be killed;
g) A tree with WJTD is often immediately adjacent to an unaffected tree, although typically, affected trees appear in clumps;
h) Trees uninjured the previous year may be injured the subsequent year.
i.) juvenile trees are much more susceptible to WJTD than are bearing trees, and usually third, fourth, and fifth leaf trees appear most at risk.
j.) the most vigorous rootstocks, cultivars and growth stages of the pistachio tree appear most susceptible to WJTD.