dies. And, in an orchard site from which old trees have been re- 

 moved recently, new trees grow poorly and do not live as long as 

 those planted on new land. 



This problem has been known for many years and is world wide. 

 It is referred to as "the peach replant problem," "the short life 

 of peach replants," "peach decline, "soil sickness" and even "win- 

 ter injury." 



The symptoms above ground are the same as caused by any condi- 

 tion that interferes with good root development and function. The 

 plant grows poorly and has a sickly appearance. Later, there may 

 be dieback of twigs and branches and the plant may even die. Below 

 ground, on declining plants, the feeder root system is poorly devel- 

 oped and inadequate. Some roots have large brown or dead areas and 

 many of the feeder roots are shriveled and dead. 



Investigators name different causes for the trouble - soil- 

 borne fungi such as Pythium spp. or Phytophthora spp. , Clitocybe 

 root rot, bacterial canker, nematodes, winter injury, drought, soil 

 too wet, high soil temperature, over-fertilizing, starved plants, 

 etc. Each of these causes has been found to be responsible at some 

 time or other in different orchards. Som.e investigators agree on 

 several causes, others do not. Most likely several conditions, 

 •either occurring at the same time or one after the other, are re- 

 sponsible. For example, it is quite common in spring for soils to 

 be wet and cold - a condition that does not favor feeder root devel- 

 opment of peach trees. But it does favor development and root in- 

 vasion by soil fungi such as Pythium and Phytophthora . As the soil 

 dries and becomes warmer, it is less favorable for these two fungi 

 but more favorable for development and invasion of roots by nema- 

 todes which further weaken the root system. As the season progresses 

 and rains are less frequent, the soil becomes even drier, and often 

 drought conditions exist, at least for a while. At the same time 

 the hot weather evaporates large quantities of water from the leaves 

 of the trees. A poor or weakened feeder root system in a soil that 

 does not have enough water and even in a wet soil cannot keep up 

 with the water demand of the tree and the stress shows up as weak 

 and poor growth of the tree above ground. Weakened trees are sus- 

 ceptible to bacterial canker, twig and branch dieback caused by 

 several fungi such as Cytospcra and Valsa , and winter injury, and 

 the whole business ends up as "decline" and dead trees. 



Rather than review in detail the extensive research that has 

 been done over the years on the replant problem, it may be helpful 

 to give some of the conclusions of some of the more recent investi- 

 gations. 



The following is from "Peach Decline in Georgia," Georgia Agri- 

 cultural Experiment Station Bulletin 77, June, 1970. It reports 

 investigations from 1929 - about 40 years. 



