13 
hammock or high pine land! are almost exempt from the disease. On 
flatwood land? the trees are less susceptible than those on light ham- 
mock, but more susceptible than those on high pine lands. 
As the blight is most prevalent on the best orange lands, with the 
exception of clayey hammock, which is rare, it is obviously impracti- 
cable to prevent the disease by planting on lands least subject to it. 
Cause.—So far the most diligent search, both in the field and in the 
laboratory, has failed to reveal the cause of blight. Judging from 
what is known of the disease, it is not improbable that it is caused by 
some minute parasitic organism, but the character of the soil to a large 
extent governs the entrance and spread of the organism. In many 
respects blight strongly resembles peach yellows, the exact cause of 
which is also unknown. Certain it is that blight can not be attributed 
directly to cold, drought, wet weather, close proximity of hardpan, or 
improper fertilizers, as is often erroneously believed. 
Is blight contagious?—As before stated, this malady in many respects 
resembles peach yellows, which latter disease is contagious by budding 
as has been proved by experiments. Numerous experiments are under 
way to determine whether blight can be introduced by buds on the 
roots or tops of trees, but so far no conclusive results have been 
obtained. The disease attacks trees in groups, as is obvious in groves 
where it exists. A year or two after a tree is blighted it is a common 
thing to see the adjacent trees show the blight on the limbs next to 
the diseased tree. All these circumstances strengthen the belief that 
the disease is of a contagious nature. 
Preventive measures.—Experience has taught that it is not only useless 
but dangerous to attempt to cure blighted trees, since it is probable 
that the disease is contagious, and that a diseased tree left in the grove 
may infect surrounding healthy trees. It is by all means the safest 
and at the same time the most profitable plan to dig up and burn all 
blighted trees as soon as they appear and plant new trees in their 
places. In many instances it would seem that prompt destruction of 
trees aS soon aS attacked has decidedly reduced the number of new 
cases aS compared with adjoining groves similar in all respects, but 
where the diseased trees were allowed to remain. In peach yellows 
the prompt extirpation of cases as they appear is the only known 
way of preventing the spread of the disease. 
In replanting, good-sized trees are preferable to small trees, as the 
latter are liable to be overshadowed and starved out by the large trees 
surrounding them. The diseased trees when dug out can be either 
1Land covered with scattering Pinus palustris and a few trees of Quercus cinerea 
and @. catesbai, all growing so far apart as to allow grass to grow so thick that 
it is burned off annually, thus preventing the growth of underbrush. 
2Much like high pine land, but low and flat, with a subsoil near the surface, 
and more undergrowth, composed largely of scrub palmetto (Serenea serrulata) and 
Ericacez. 
