270 



THE AGRICULTURAL NEWS. 



August 17, 1912. 



FUNGUS NOTES. 



MISCELLANEUUS INFORMATION. 



In the following article a few iniscellaneou.s points of 

 interest ■will be dealt with relating to the occurrence of 

 different species of fungi in the islands. 



ENTOMOGENOUS FUNGI In a communication recently 

 received from the Agricultural Superintendent in St. Lucia 

 it is stated that the white-headed fungus (Ophioiiertria 

 corricota) parasitic upon scale insects was particularly preva- 

 lent in the southern district of that island during the month 

 of July, so much so that its presence caused some alarm 

 until its usefulness was indicated It is perhaps hardly 

 necessary to point out that this fungus has never been 

 known to cause any damage to plants and that its activities 

 are entirely confined to the insects upon which it lives. In 

 other parts of the island, particularly in the northern district, 

 it was entirely absent. It has been estaVjlished artificially at the 

 Experiment Station and upon a neighbouring estate, and 

 since this is .so, it would appear that the fungus might also 

 be introduced into other districts where it is not at present 

 found. The Assistant Agricultural Superintendent has pro- 

 vided the informatinn that artificial inoculation is greatly- 

 assisted if the inoculated trees are sprayed with water everv 

 morning and evening for a week after the infected leaves 

 have been tied in, more especially in dry weather. The 

 presence of the fungus would appear from the information 

 given to be largely dependent on the moisture conditions, 

 since the rainfall at the southern end of the island is usually 

 higher than at the north. Generally speaking, however, the 

 conditions in St, Lucia are very favourable to the develop- 

 ment of the fungus parasites of scale insects. Besides the 

 white-headed fungus {Ophionectria corcicola) and the three 

 other species of scale insect parasites that have been known 

 to be present for some time, there are also two species of 

 Aschersonia. One is A. turbmata, that lives probably upon 

 the mango shield scale (Coccus 7nangiferae). It was referred 

 to in the Agricultural Neiva, Vol. X, p. 190, under the name 

 Hypiichrella o.ryspora, but according to information received 

 from Mr. Fetch, the Government Mycologist in Ceylon, this 

 name is incorrect. The other species is as yet unidentified, 

 but it was found to attack a species of Coccus on rose apple 

 (Eugenia Jamhos) growing by the roadside in the Forestiere 

 district. It appeared to attack also specimens of the glassy 

 star scale (Vinsonia stelUfera), which was common on the 

 leaves of the plant, but this was not actually the case. 



RED RUST OF LIME LE.WES. Some Specimens of lime 

 leaves have recently been received from St. Lucia which 

 showed peculiar raised rusty-brown patches on their upper. 

 and occasionally on their lower, surfaces. The patches varied 

 in size from 1 to 5 mm., and on examination with a hand 

 lens were seen to be covered with fine red hair.^, each of 

 which terminated in a small round knob. The patches are 

 caused by the flat plates of an alga belonging to the genus 

 Cephaleuros. This minute plant, although it is provided 

 with chloroiihyll and can obtain its own carbon-supply is 

 undoubtedly parasitic upon the leaves, but the injury it 

 inflicts is confined to the tissues immediately below it and it 

 probably does not interfere with the normal functions of the 

 leaves sufficiently to cause any serious damage. In the cells 

 forming the terminal knobs that arise from the surface of 

 the plate, motile zoospores are produced, which are liberated 

 and germinate when the surfaces of the leaves are moist, and 



thus produce new algal plates. The same or a similar species 

 has been previously recorded upon different kinds of Citrus 

 in Grenada. The record is of interest because an allied 

 species (Cephaleuros mijcoidea) is responsible for the 'red 

 rust' of tea bushes in India. There, the alga occurs on the 

 leaves and young twigs, on the latter of which it forms 

 bright-red patches that cause the serious injury to the 

 bushes. The presence of the alga on the leaves is not of any 

 great importance. As far as is known at present, the local 

 species has not been observed to attack Citrus twigs, and is 

 probably of but little economic importance. 



Fig. 7. Eutyp.a. Caulivoe.\ on Hf.vea. 



BL.\CK ROOT DISEASE. It has recently been determined 

 that Rosellinia hunodes, the fungus causing black root disease 

 of limes, cacao, and pois doux (Inga laurina) in Dominica, 

 occurs in Grenada, where it was first found on Castilloa 

 plants. It has been recorded in the same island on the 

 pigeon pea and more recently on young camphor plants. 

 The species of Ro.sellinia responsible for cacao r".ir, disease in 

 St. Lucia is different from R. Ijiinodes, as the pei ithecia are 

 much larger and are, moreover, smooth and dark-brown 

 rather than black. The identity of the St. Lucia species is at 

 present undetermined, as none of the perithecia examined 

 were mature and no spores have been found in them. A new 

 host plant, the horse bean (Canavalia ensiformis) has been 

 lately recorded for this parasite. It would appear from the 

 number and varied nature of the plants that have been found 

 to be attacked that almost any plant whose roots were in con- 

 tact with infected material might succumb to this disease. 

 An outline of the treatment to be given in cases of this and 

 similar diseases has already appeared in the Agricultural News, 

 Vol. XI, p. 190, and experiments are in progress to test some 

 other methods. 



