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tammock or high pine land (^) are almost exempt from the disease. 

 On fl.itwood land {'^) the trees are less susceptible than those on light 

 hammock, 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 stronglj^ resembles peach yellows, the exact cause 

 of which is also unknown. Certain it is that blight cannot be attribu- 

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

 or improper fertilisers, as is often erroneously believed. 



Is blight contagious? — As before stated, this malady in many re- 

 spects 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 bhght on the limbs next to 

 the diseased tree. All these circumstances strengthen the belief that 

 the disease is of a contagious nature. 



Preventiv 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 prevent- 

 ing 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 

 hauled away and burned, or better cut up and burned on the spot, thus 

 avoiding any possibility of spreading the disease through the grove. 

 It has been abundantly proved that trees planted where blighted ones 

 have stood are not more likely to contract the malady than any other 

 in the vicinity, and in no case are they liable to blight before they 

 begin to bear. 



(1) Land covered with scattering Pinus palustris and a few trees of Quercus cin- 

 trea and Q. cateshcei, all growing so for apart as to allow grass to grow so thick 

 that it is burned < ff annually, thus preventing the growth of underbush. 



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

 and more undergrowth, composed largely of shrub palmetto fSerenoa serrulata y 

 and Ericaceae. 



