4ti 



THE AGRICULTURAL NEWS. 



J AMI V.B1 30, 1915. 



FUNGUS NOTES. 



TWO BEAN DISEASES. 



Two well known diseases to which beans of the genus 

 Bhaseolus are subject are described in Special Bulletin 68, of 

 the Michigan Agricultural College Experiment Station, by 

 •I. II. Muncie. Descriptions of their field characters are given 

 m> considerable detail, and form the basis of the summary pre- 

 sented below. Little appears tobeknown astothe occurrem 

 it bean diseases in the West Indies, the crop usually being 

 i i\ subsidiary one, and receiving little attention. In con- 

 [Uence nl the regular importation of seed from the United 

 States, the probability of the occurrence bere of both the 

 diseases in question is verj cot dderable, and the following 

 information may enable them to be recognized. Bacterial 

 leaf diseases ol beans similar to. or identical with, "blight' are 

 net uncommon in Barbados. 



Bean anthracnose, due to Colletotrichum cindemuthi- 

 anntn. is a disease which liegins from infected seed, appears 

 .mi the vnii ng si ''J 1 1 1 i.e. -, ami ultimately infests the leaves, stems, 

 mil pods of the developed plants. The fungus penetrates the 

 pods t" the seeds within, upon which spots are developed 

 which necessitate the sorting by hand of the crop, and form 

 a starting point for a new cycle of disease. The spots appear 

 On the seeds as sunken Mack or brown specks in the case of 

 light attack, or as brownish or blackened spots, usually in 

 the form of a ring with a dark or rifted centre, where the 

 attack is severe. On the seed-leaves, circular or kidney- 

 shaped blotches appear, which may enlarge until the whole 

 leaf is involved. Elongated cankers are produced on the 

 >teins, and many young plants are lost from the direct or 

 indirect consequences of stem and root infection. Young 

 leaves may be crinkled owing to the effect of the fungus on 

 the margins; older leaves are affected mostly on the veins, 

 and the portion of the leaf blade beyond the attacked vein 

 turns yellow and dies, for want of water. On the pods the 

 lesions start as small reddish pin-point spots, which enlarge 

 into circular or kidney-shaped sunken areas with a raised 

 rim. Yellow or pink spore masses are produced in the 

 centres of these spots. Severe infestation occurs as a conse- 

 i|iience of continued wet weather, and a general yellow 

 appearance, due to the dying of the leaves, is then recogniz- 

 able in the fields. 



Spraying with Bordeaux mixture is a measure of 

 doubtful efficacy, nor is any other cure known. According 

 to M. I'. Ban us {Phytopatltology, I, 190), varieties which 

 have been found resistant to certain strains of the 

 fungus are attacked by other strains, and no com- 

 pletely resistant variety has yet been produced. Freedom 

 in the disease can howevei be secured by taking precau- 

 tions against planting infected seed. Pods must be selected 

 which have no spots whatever upon them. It is uol 

 sufficient to select unspotted ieed, since a slight infection 

 may not be noticeable. An infection so slight as this upon 

 i pod would have little significance, since the fungus would 

 not have penetrated to the seeds within. It is advisable, 

 however, in order to prevent infection from such a source, or 



ii merely adherent s] i dip the pods for ten minutes 



in corrosive sublin <.\ part to 1,000 of water). 



obtained should be used to ] I plot on 



■ lean ground, t ' fcer this tn m at mould at 



worst be elimination by hand-pull 



The second di in blight, is caused by Ba 

 phaseoli Thi in ight cases, 

 yellow spots or bloti hes, not d ii Fn utly 



on the side of the seed which was attached to the pod; in 

 ases, yellowing and shrivelling of the whole seed. 

 On the seed leavi mail amber-coloured spots appear, with 

 which ma j bi a — iated a light fellow slime. On the foliage 

 Leaves the disease produces irregular water soaked areas, 



which are uSUall) bordered by distinct yellow Or red lines. 



These areas gradually* enlarge until the entire margin, or 

 half the leaflet, maj be involved. The watery areas later 

 l.e,,, me brown and dry. < in the pods, watery pustules 



first fori I, which develop into anil ier nil. Hired 



irregular blotches with uneven green centres; clumps of 

 the bacteria ooze out, and dry into yellow crusts on both 

 leaves and pods. The general appearance of a field, when 

 the prevalence of humid weather conditions has led to a 

 severe infestation, is described as suggesting that the plants 

 had been drenched with hot grease. At a later stage the 

 older leaves look dry and burnt, and excessive new growth 

 occurs in the attempt to provide mw foliage. Fruiting is 

 seriousl) interfered with, and the pods cease to till out. 



No fully effective means of control is known. The 

 germs are able to resist drying for a long period, and become 

 widely spread, so that probably reinfection does not entirely 

 depend on seed. The measures recommended for anthracnose 

 should, however, also reduce considerably the incidence 

 blight. 



CITRUS CANKER. 



In the lust number of this Journal (p. 14) infor- 

 mation was given concerning citrus canker. This may 

 now be extended by the abstracts, appearing in 

 Phytopathology for December, of two papers to be read 

 at the Annual Meeting of the American Phytopatho- 

 logical Society. 



citrus canker. A. B. Massey. A serious disease, 

 citrus canker, appeared in south Alabama and localities of 

 Florida about two years ago, but came to our attention in 

 January 191-1. 



By isolation cultures, artificial inoculations, and reisola- 

 tions the cause has been proved to be due to a species of 

 Phoma. 



It has been found on a number of different species of 

 citrus, but its greatest damage is confined to the grape fruit, 

 and hardy orange ( Citrus trifoliata) stock. It attacks seriously 

 the fruit, twigs, and leaves of the grape fruit, causing the 

 leaves to drop, and injuring the marketable quality of the 

 fruit. In the hardy orange no case of fruit infection has been 

 found, but the twigs and leaves are heavily attacked, causing 

 defoliation and serious injury to the young twigs. 



THE CTTBUS ' VNKER SITUATION. 1!. Kent Beattie. 

 A new oriental disease, far exceeding the chestnut bark disease, 

 in infectiousness, has recently made its advent in the Gulf 

 States. The citrus canker occurs on all species of citrus, but is 

 especially severe on grape fruit. It develops upon the leaves. 

 stems, and fruit. It may kill young trees, but does not 

 develop girdling ikers on older stock. Its chief injury 

 is to the fruit. The Satsuma orange is highly resistant. 



The disease ivas brought from Japan on Satsuma, or 



Citrus trifoliata oek, and has been nursery distributed 



throughout the Gulf States, Quarantine measures, and the 

 destruction ol infecte^d trees and nurserj stock bj burning are 



Used tO combat it. 



This disi a splendid illustration ol the danger 



to which we an constantly exposed from plant diseases 

 gni; d in far off coi d< rs of the earth. 



