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THE AGRICULTURAL NEWS 



OCTOuER 19, 19lb. 



PLANT DISEASES. 



GRAY MOULD OF CASTOR BEANS. 



( unsidering thf iiicrease<i attention which is being 

 given to the ^-ultivatioii of the Castor Oil plant an 

 article on the above subject bj H. K. Stevens, which 

 has been issued as Pre>^c Bulletin, Xo. 39ii of the Uni- 

 \ersitv of Florida Agricultural Experiment Station, is 

 Teprinttd below, as i>f interest in connexion with this 



crop. 



A fungus disease that has appeared on the castor bean 

 within the last two weeks is causing serious injury to the 

 crop in many regions ol.the stale. It is a gray mould that 

 attacks the fruit spikes -n various stage.s of development. 

 The unopened flower buds, flowers, and nearly mature pods 

 :)re attacked by the fungus. In some cases fiom 50 to 90 

 per cent, of the plants in a field are affected with the disease. 

 Rain and shady conditions seem to favour a rapid spread of 

 this mould. 



At'lT.Alt.VNCE. 



The disease is at once recognized by the grayish, webby 

 mass of fungus growth on the aflfected heads. In well 

 developed cases from one-half to three-fourths of the affected 

 lead will be enveloped by a gray, webby mass more or less 

 jX'wdery in appearance. Pods and flowers in a head that 

 are killed by the fungus become brown and covered with a 

 dusty gray, powdery mass which contains countless numbers 

 of spores. The disease appears to start at one point and 

 spreads rapidly until the entire head is affected. The fungus 

 also attacks the stem of the fruit spike and flower stems caus- 

 ing at first a dark, watery rot. The affected part soon dies, 

 turns brown and becomes dry. 



The first appeannce of the disease is marked by a dark 

 coloured spr)t or stain usual!\ on one or more adjacent pods. 

 This spotting sometimes appears first on the stem of the fruit 

 spike or on the pod stems. The affected ti.ssue is found to 

 be rotted and watery. X'^ fungus growth is visible at this 

 stafie. and the remainder r.f the pods or heads appears green 

 and normal. Three or four day> later a fourth or half of the 

 head may be enveloped with a grayish growth, and all part.-- 

 covered by the fungus are killed. 



lAUSE. 



The disease is caused by a fungus which appears 

 to be a new species of Botrytis. Specimens were sent 

 to Mrs. F. W. Patterson, Bureau of Plant Industry, 

 I'nited States Department of Agriculture who reports the 

 fungu.'; as an undescribed species of Botrytik. Very little 

 is known of its liabit.s at present and it does nfit seem to have 

 been reported on the CHstor bean before. Under moist con- 

 dition.s the fungu.« produces spores (seed) in countless numbers 

 in the webby growth enveloping the affected heads. These 

 are readily scattered by the wind and insects and infect 

 other fruit heads. 



The fungus is very active under moist shady conditions 

 and during peri'>ds of rain and cloudy weather it may become 

 verj- destructive, especially when beans are closely planted 

 and are making vigorous grfiwtli. 



'..■O.N-IKOI.. 



The rapidity with which this fungus Las developed and 

 hpread within the last two weeks, and the nature of the castor 

 b?rin plant, offer little enrouragement for an easy method of 

 cf.ntrol. Where it is widely .scattered thrr.ugh a field very 



little can be done to protect the fruit heads that may develop 

 during the rainy season. After the dry season comes on the 

 disease will probably cause small loss. 



In fields where the disease is just appearing and only at 

 small number of heads are affected, further loss may be [»re- 

 vented if immediate steps are taken to suppress it. All 

 affected fruit heads should be cut off and put directly int» 

 a pail of kerosene and carried from the field and burned. 

 Plants from, which affected heads are cut should be thorough- 

 ly sprayed with Bordeaux mixture, 4-4-50 fornuila, to kill' 

 spores that have kdged on the leaves and stems. The 

 flower and fruit heads on all plants in the vicinity of dis- 

 eased ones should be thoroughly sprayed with Bordeaux. 

 An area of 50 to 100 feet beyond all diseased areas should be 

 sprayed and inspected fretiuently for new outbreaks. 



PLANT QUARANTINE. 



In the Montl'lt/ Bullet in cf the State (Ji'in-iaii'non 

 o/ Agriculttire, California, June IftiN, appears a note, 

 which is reproduced below. The old Latin tag wcuild 

 seem very appropriate to our West Indies in this 

 matter. Ik to fxtivla nurratvr. 



From Australia comes the report that citrus canker has- 

 made its appearance in the commonwealth. True to tradi- 

 tion, tfce press does not hesitate to jump on the horticultural 

 officers, and lay the blame for allowing the importation at 

 their door. 



This is in a large measure to be expected. Speaking in 

 the abstract it should be stated that there are many aspects 

 of such problems that are seldom brought to the notice of the 

 public. 



The assertion is ventured that there are horticultural 

 officials who have had a chance to wear themselves out 

 trying to si|ueeze from a reluctant legislature funds fcr 

 the purpose of providing a means of preventing the 

 introduction of some plant pest or disease that may 

 be causing consternation in some other part of the 

 world, and which it is realized will sooner or later be 

 brought to their shores. Nor is the legislature entirely 

 to blame. Such bodies as a rule are generally composed of in- 

 dividuals largely ignorant of the bionomics of insect pests and 

 plant diseases, without trainmg in the estimation of evidence 

 in this line, and withal unable to appreciate the extent or 

 imminence of danger which m.iy he anticijiated from this 

 source. The responsibility may often be traced farther back 

 to the fruit growers themselves who, with full knowledge of 

 the true significance of the menace, wait for someone else to 

 take the initiative until the eleventh hour, when the pest in 

 (jueslion ap|X'ars, and their chance has vanished. This atti- 

 tude is particularly reiirehensible, as they must surely under- 

 stand fully that whatever happens they will be the hisers. 



As a result of this combination of circumstances pleas 

 for preventive rather than remedial measures too often 

 receive a deaf ear. Whatever the reason, the results are 

 always the same. In tracing the course of introduced plant 

 pests and diseases it is an unwritten law that the govern- 

 ment which has failed to take necessary precaution in provid- 

 ing adequate means to prevent the introduction of undesirable 

 alien plant pests and disea-ses, sooner or later, but neverthe- 

 less surely, has an opportunity to dig down into its coffers tr. 

 the extent of about one hundicd times which the amount of 

 a proper insurance against this class ..f niuIesiraUle alien.- 

 would have cast. 



