29 



high pine land (2) are almost exempt from the disease. On 

 flatwood land (3) the trees are less susceptible than those on 

 light hammock, but more susceptible than those on high pine 

 lands. 



As the blight is more prevalent on best orange lands, with 

 the exception of clayey hammock, which is rare, it is obviously 

 impracticable 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 im, 

 probable 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 cannot be attributed 

 directly to cold, drought, wet weather, close proximity of 

 hardpan, or improper fertilisers, as it is often erroneously 

 believed. 



Is Blight Contagious ? — As before stated, this malady in 

 many respects resembles peach yellows, which latter dise >se 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 shew 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 



(2) Land covered with scattering Pinus Palustris and a few trees of 

 Quercus cinerea and Q. Catesbaei, all growing so far apart as to allow grass 

 to grow so thiok that it burned off annually, thus preventing the growth 

 of underbush. 



(3) Much like high pine land, but low and flat, with a subsoil near the 

 surface and more undergrowth, composed largely of shrub palmetto, 

 (Serenoa serrulata) and Ericaceae. 



