R. N. Tandon

The nutrition of Colletotrichum gloeosporioides Penz

Colletotrichum gloeosporioides could grow and sporulate on a wide range of pH (viz., from 3.0 to 8.5). The best growth was obtained at pH 6.0. Mannitol proved to be the best carbon source. Good growth and sporulation were also observed on maltose, glucose, galactose and sucrose. Nitrates supported better growth than ammonium compounds. Glutamic acid was found to be the best amino acid. Nitrites inhibited the growth completely at acid pH values but they supported growth at alkaline pH. Mannitol-glutamic acid was most suitable carbon-nitrogen combination for growth. Magnesium sulphate was the only sulphur source which was good both for growth and sporulation. The organism could not grow on media lacking carbon, nitrogen or sulphur.

Changes in free amino acids of tomato fruit under pathogenesis

In th i s report , low i n t ens i t y u l t r a s o u n d ha s been used to affect t he visco-elast ic proper t ies of ceils of Helodea densa. Cont inuous u l t r a s o u n d (t MHz) was i r r ad ia ted on leaves in con t ac t w i th a lead z i rcon ium t i t a n a t e c rys t a l v i a a layer of wa te r a n d a g lasspla te (see [I]). Ef fec t s on t h e visco-elast ie proper t ies of t he p r o t o p l a s m were de t e rmi ned b y s t u d y i n g differences in t he a m o u n t of cells in wh ich t he chloroplas ts were displaced u n d e r a f ixed cent r i fuga l force (920 g). Th i s m e t h o d has been ex tens ive ly used in s tud ies of t hese cells [2]. I n t h e expe r imen t a l m e t h o d used, a leaf was ha l ted a long t he va scu l a r bundle , one hal f be ing used as a control . The o the r half was i r rad ia ted for 3 m i n w i t h a f ixed in tens i ty . The centr i Iuga t ion per iod (which foIlowed i mmed i a t e l y , b o t h ha lves be ing centr i fuged) las ted for 3 min . F r o m p h o t o g r a p h s of t he b o t h ha lves (magn. 35 X) t he n u m b e r of cells in which the chloroplas ts were displaced on to t he bas ipe ta I wall were de te rmined . The cells of t he u n d e r sur face of t he leaves were a lways observed (cf. [2]). The pe rcen tage of ceils af fected is shown in Fig. 1 A E , for t he di f ferent peak vol tages appl ied to t he crys ta l . I n t h e s ame w a y t h e m e a n n u m b e r of cells affected (as %) is r ep resen ted in Fig. 1F.

Some pathological studies on botryodiplodia theobromae pat. causing banana rot

B. theobromae Pat. was found to be pathogenic on banana (Musa paradisiaca L.) variety “Bhusaval”. Its symptoms and morphology were studied. Inoculation tests were performed and the pathogenicity of the organism on its host was confirmed. It was also found that injury to the fruits enhanced the chances for infection. Percentage rot of banana fruits was found to be maximum at 25° C and 30° C and minimum at 7° C and below. An external supply of humidity always favoured the advancement of the disease on the fruits. Mode of germination of the spores was studied. Highest percentage germination ofB. theobromae was obtained at 25° C. 1 % host extract solution also gave the maximum results. Cross inoculations revealed that the pathogen was capable of infecting other varieties of banana and fruits of other plants as well. The longevity of spores and their thermal-death point have been determined.

Three new leaf-infecting fungi from allahabad

The fungi described in this paper were isolated during the course of a detailed survey of leaf-spot diseases of Allahabad and adjacent regions. A comparative s tudy indicated the forms reported here viz., Colletotrichum sp. from Sapindus lauri/olius VAHL., Pyrenochaeta sp. from Gardenia florida L. and Phoma sp. from Ehretia acuminata BR., to be distinct from the hitherto described species of the respective genera. They are thus reported here as new species. 1. Colletotrichum sapindi sp. nov. On living leaves of Sapindus lauri/olius VAHL., Alfred Park, Allahabad, September 1963, leg. S.C. (Fig. 1). Symptoms of the disease: the infection started near the margin where a small area of lamina turned light cinnamon drab. This area gradually increased inwards and its colour changed to cinnamon drab. Very minute acervuli appeared after a few days on the

Studies on the pectolytic enzymes ofaspergillus terreus Thom

Aspergillus terreus, the causal organism of fruit-rot of apples produced pectin methylesterase (PME) and depolymerase (DP) on a number of substrates. The production of polygalacturonase (PG) was restricted to few substances only and appeared to be adaptive. PME as well as hydrolytic activities were maximum when cultures were incubated at 25°C. The pH of the substrate for maximum PME and hydrolytic activities was 5.5 and 5.0 respectively.

Utilization of carbohydrates by Helminthosporium rostratum drechs. and Deightoniella torulosa (SYD). Ell. (SYN. Helminthosporium torulosum SYD.)

Utilization of four carbohydrates, viz. D-glucose, D-fructose, sucrose and starch, byHelminthosporium rostratum andDeightoniella torulosa isolated from the leaves ofJasminum arborescens Vern. “Newari” and banana (Musa paradisiaca L.) fruits respectively, was exhaustively investigated by chromatographic technique. Chromatographic analysis of the culture medium revealed that both the organisms assimilated glucose earlier than fructose. The hydrolytic products of sucrose and starch (only glucose was detected) could be traced in the medium. In all cases dry weights of both the organisms continued to increase upto 15 days except inH. rostratum growing on starch where it decreased after 10th day. The pH changes of the media showed a drift towards neutrality.

Studies on fungal diseases of some tropical fruits IV. Some new fungi

Four new species which includedSordaria allahabadensis on flowers ofCarica papaya L.,Thielavia appendiculata on leaves ofPunica granatum L.,Phomopsis amraii on leaves ofMangifera indica L. andPhoma punicae on twigs ofPunica granatum L. have been described.

Sulphur and phosphorus requirements of three fungi causing diseases in storage

The effect of different sulphur and phosphorus compounds on the growth and reproduction of three fungi causing storage rot, viz.,Fusarium solani, Botryodiplodia ananassae andMacrophomina phaseoli has been studied. Sixteen different sources of sulphur were used and out of them magnesium sulphate was found to be most favourable for the growth and reproduction of all the three fungi. Sodium sulphite and sodium bisulphite were toxic. Potassium metabisulphite prevented growth ofF. solani and M. phaseoli while it supported moderate growth ofB. ananassae. Only magnesium sulphate could induce the sporulation ofB. ananassae while sporulation and sclerotial development ofF. solani andM. phaseoli respectively varied with the type of sulphur sources used. Optimum concentration of magnesium sulphate was also determined and it was found that the growth and sporulation ofF. solani andB. ananassae were best at 0.375 g/l and 0.75 g/l.M. phaseoli tolerated higher doses of this substance as the best growth and excellent sclerotial development were recorded at 3.0 g/l (the maximum concentration used). Phosphorus was found to be essential for the present fungi as none of them could grow in complete absence of this substance. Onthophosphates and nucleic acid, were found to be favourable sources for growth and reproduction of the 3 organisms.

Post-harvest diseases of tomato in india

A systematic account of nine fungal diseases of tomatoes caused byAlternaria tenuis, Colletotrichum dematium, Cladosporium fulvum, Fusarium roseum, Malustela aeria, Myrothecium roridum, Oospora lactis f. parasitica, Phoma sp. andRhizopus nigricans during storage has been given. Except Oospora rot the other diseases included in the present paper have not been recorded previously from India. Post-harvest decay of tomatoes due toMalustela aeria has not been described from any part of the world and is new to science.

Sulphur requirements of certain isolates ofAlternaria tenuis Auct

The sulphur nutrition of three isolates ofAlternaria tenuis Auct., isolated from the diseased leaves ofMangifera indica L.,Musa paradisiaca L. andPsidium guajava L., was studied. They were grown on the medium devoid of sulphur as well as on media containing various sources of sulphur viz., ammonium sulphate, sodium hyposulphite, sodium thiosulphate, magnesium sulphate, potassium sulphate, potassium metabisulphite, zinc sulphate and thiourea. Sodium hyposulphite, sodium thiosulphate, magnesium sulphate, potassium sulphate and zinc sulphate were generally found to be satisfactory sources for the growth of all the isolates under study. Poor growth of the different isolates was observed on the medium devoid of sulphur.