16 BULLETIN" 1038, U. S. DEPARTMENT OF AGRICULTURE. 
highly probable that pecan rosette belonged to the group of non- 
transmissible chlorotic diseases caused by improper nutritive supply 
or injurious physical conditions. The possibility of the presence of 
some parasitic organism was not entirely precluded, but it was 
thought highly probable that the ultimate cause would be found in 
some lack of balance in nutritive supply, or possibly in some toxic 
substance or substances in the soil. These conclusions were based 
entirely upon the results of field experimentation. 
Miller (54) observed that buds from rosetted trees worked upon 
healthy stock in most instances grew into normal trees, but that 
when a tree was decidedly rosetted its buds would sometimes develop 
the disease when worked upon healthy stock. He is of the opinion 
that rosette is due to soil relations and observed that in dry seasons 
the disease is more prevalent. Rosette and a proper amount of 
moisture, he says, do not go together. Impoverished soil, lack of 
humus, overstimulation of growth, and use of improper fertilizers 
all favor rosette. He states that the severest cases are incurable, or 
at least not curable by practical means. 
Fawcett (33) refers to pecan rosette in a short paragraph, and 
Crittenden (26, pp. 44^-45) briefly summarizes the work of Orton 
and Rand. 
Matz (51, pp. 139-141) in a bulletin relating to various pecan dis- 
eases and insects devotes a short section to rosette. He states that 
the disease apparently occurs on all types of soil and at all seasons, 
but that wherever it occurs it is most abundant during late summer. 
He also says that rosette is more abundant on higher and more ex- 
posed soils than in low and more protected situations. After 
briefly describing the signs of the disease he adds that many of the 
dead leaves adhere to the branches throughout the winter unless 
blown off by strong winds. The disease is favored by planting in 
open, sandy soil or where a hardpan exists near the surface. 
McMurran (50) in a paper dealing with field experiments and 
observations states that rosette is generally considered to be the most 
serious pecan disease. It is found upon a wide range of soil types 
and under various conditions of culture and fertilization; but one 
factor, he says, appears to run through it all. On the river flood 
plains of Southern Louisiana the disease is practically unknown. 
Here the soil is deep and black and of high fertility and presumably 
of high water-holding capacity as compared with the typical sand, 
sand-clay, and clay soils of the Atlantic and Gulf Coastal Plains 
where the disease is so prevalent. In Georgia and Florida probably 
90 per cent of the affected trees are on hilltops and slopes. All 
cases on the bottoms that have been examined were found to be in 
deep sand or in a clay or sand-clay soil underlain at 2 or 3 feet by 
sand. It was noted further that large healthy trees 5 to 10 years old 
