ROSETTE OF PECAN TREES 13 
DISCUSSION 
In orchards affected with rosette the turning under of leguminous 
crops has proved a highly successful remedy. It is attended by an 
increased organic-matter content of the soils, which not only furnishes 
a steady and gradual supply of nitrogen for the trees but improves 
the physical condition of the soil and increases its moisture-holding 
capacity. The data procured in the orchards investigated show a 
close relation between the humus content of the soil and the rosette 
of pecans. As the organic matter in the soil increased, the rosette of 
the orchards decreased and gradually disappeared. 
Methods of increasing the humus content of a soil vary, but an 
easy and inexpensive way is by the use of green-manure crops. The 
application of large quantities of stable manure would probably give 
the quickest results, but stable manure is expensive and difficult to 
obtain. The natural growth of grass and weeds allowed to decompose 
on the ground would likely help somewhat. Applications of ordinary 
commercial fertilizers alone apparently do not serve as a remedy for 
the rosette of pecans. 
This statement seems applicable also to the rosette of apples. 
Morris, 3 working with apples on western soils, obtained no apparent 
improvement with apple rosette by the application of chemical fer- 
tilizer, but orchards in which leguminous cover crops were grown out- 
grew the diseased condition in three to five years. The practice of good 
farming methods which maintain a high degree of soil fertility is as 
essential to successful pecan growing on upland soils as it is in the 
growing of any farm crop. Fertile soil is necessary to develop nor- 
mal, healthy trees capable of producing good crops of pecans. 
In order to determine the relation of the organic matter of the soil 
to the general growth of pecan trees and the production of nuts, other 
rosette-free orchards were examined. The data are given below. 
EXAMINATION OF THE SOIL OF GOOD AND OF POOR SECTIONS 
OF ORCHARDS FREE FROM ROSETTE 
The soils of eight orchards containing no rosette in which different 
cultural methods had been practiced were analyzed for nitrogen and 
organic matter and their acidity determined, so as to ascertain the 
relation of these factors to the condition of the orchards. In these 
orchards, each having a uniform soil type, two cultural methods had 
been practiced. Each presented an opportunity to study the effect 
of soil and orchard management or fertilization on the soil and on 
pecan growth and yield. 
The soils examined were from orchards situated in Georgia, Florida, 
and Alabama and are reported as being well adapted to pecan culture. 
The soil samples were collected in 1921 and 1922, and the orchard 
record was made at that time. The data are given in Table 11. 
Comparisons should be made between the two sections under 
different cultural treatments in each orchard (Table 11). The soil 
types and also the tree varieties in each section of each orchard were 
the same. The differences shown in tree growth and yield are 
apparently due to cultural treatment. The effect of the soil treatment 
on the organic matter and nitrogen of the soil is striking, and invari- 
ably the greater organic matter and nitrogen content are correlated 
with good tree growth and yield. 
■ Morris, O. M. Apple rosette. Wash. Agr. Exp. Sta. Bui. 177, 30 p., illus. 1923. 
