The effectiveness of soil fumigation in greenhouses in the control of tomato stunt caused by the fungus Pyrenochaeta lycopersici and of tomato root anthracnose caused by Colletrichum atramentsrium (syn. C. coccodes) is highly profitable despite quite significant costs of the procedure

Stem canker of tomato caused by a distinct pathotype of Alternaria alternata became a problem in Japan since 1977. It affected only tomato plants of cv. "First" and its derivatives, which are the most popular ones for glasshouse production. The causal pathogen produced in culture a host-selective toxin (al-toxin) that is highly toxic only to susceptible tomato cultivars. Elegant tests using al-toxin revealed that the susceptibility (or sensitivity) of tomato to the disease (or al-toxin) was controlled by a major single gene locus, expressed as incompletely dominant, however, cv. "First" tomato was found to have homozygous susceptible gene and highly sensitive to both the toxin and stem canker. Using the toxin solution as a screening agent, mass screening for stem canker resistant in "First" tomato seeds was performed. The seedlings that survived the toxin treatment showed some degree of damage, indicating that mutation might have occurred from susceptible homozygote to heterozygote. A quarter of S1 progenies of the mutant was confirmed to be completely resistant to both toxin and stem canker, and hold almost useful characters which existed in "First" tomato, those named as new cv. "Al-First" homozygously resistant to stem canker.

Transmission and scanning electron microscope studies of broccoli florets affected by head rot, at various stages of disease development, strongly indicated a bacterial etiology for the disease. Bacteria isolated from diseased heads using standard techniques failed to reproduce symptoms in pathogenicity tests. However, a modified isolation technique, using broccoli heads showing incipient watersoaking symptoms, yielded a fluorescent pseudomonad which reproduced disease symptoms readily in glasshouse and field tests. The pathogenic bacterium was identified as a highly pectolytic pathovar of Pseudomonas marginalis. The bacterium also caused the rotting of potato, tomato and swede turnip slices, and also of intact and detached tomato fruit. However, it was not pathogenic on lettuce, parsnip or lucerne, and also failed to rot carrot slices.

Some properties of various isolates of tobacco mosaic virus were examined. Virus isolated from tobacco (isolate T), tomato (isolate To)and pepper (isolate P) showed different symptoms on test plant. T isolate produced light and dark green mosaic and slight crinkle. To isolate produced necrotic local lesion on inoculated leaves. P isolate produced mild light and dark green mosaic and malformation. Virus isolated from tobacco, tomato and pepper showed different symptoms on Nicotiana tabacum Linn. T isolate produced mosaic and slightly crinkle leaves. To isolate produced necrotic local lesion on inoculated leaves. P isolate produced mild mosaic and malformation. T-4 isolate produced severe green and yellow mosaic leaves. T-1, T-2 and T-3 isolates produced mosaic. Types and symptom of host range of various isolates were similar to each other. They caused either systemic reaction or local reaction on plants from Amaranthaceae, Chenopodiaceae and Solanaceae. Serological relationships among these isolates were determined against antiserum of T isolate by using agas-gel double diffusion test and immunoelectron microscopic method (IEM). To, p, t-1 and T-3 isolates were identically related to T isolate where T-2 and T-4 isolate were distantly related to T isolate on double diffusion test. IEM were also able to trap virus particles of these testing isolates, with no difference on the number of trapped particles, when antiserum against T isolate was employed. In cross protection test prior infection with tobacco isolate was found to prevent subsequent infection by tomato isolate or pepper isolate. Any plant that is infected with pepper isolate was found to prevent subsequent infection by tomato isolate.

A brief review discusses the results of a reported study on the incidence of food reactions during the first 3 years of life, conducted in 480 affected children. Some of the complaints believed to be caused by specific foods were verfied by challenge tests, but a number were not. However, ca. 76% of reactions blamed on fruits and fruit juices (36% of all complaints) were reproduced by challenges, with the most commonly implicated fruits being citrus, tomato, apple, and grape. A technical commentary to this study is appended.(mjs)

The presence of bacterial wilt of peanut caused by Pseudomonas solanacearum I.F. Smith is hereby reported. Isolation and pathogenicity tests were conducted. Inoculation experiments on tomato, eggplant, peanut, pepper, tobacco, and abaca indicated that the peanut isolate belongs to race 1. Biochemical tests showed that it belongs to biovar 3. Of the twenty-one selected promising peanut cultivars and advanced IPB lines/accessions evaluated for resistance by scalpel-leaf-clip method in the greenhouse, five peanut lines were highly resistant, six lines were moderately resistant while the rest were susceptible to highly susceptible.

Horsegram yellow mosaic disease was shown to be caused by a geminivirus; horsegram yellow mosaic virus (HYMV). The virus could not be transmitted by mechanical sap inoculation. Leaf dip and purified virus preparations showed geminate virus particles, measuring 15-18 * 30 nm. An antiserum for HYMV was produced and in enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) tests HYMV was detected in leaf extracts of fieldinfected bambara groundnut, french bean, groundnut, limabean, mungbean, pigeonpea and soybean showing yellow mosaic symptoms. Bemisia tabaci fed on purified HYMV through a parafilm membrane transmitted the virus to all the hosts listed above but not to Ageratum conyzoides, okra, cassava, cowpea, Croton bonplandianus, Lab-lab purpureus, Malvastrum coromandalianum and tomato. No reaction was obtained in ELISA and ISEM tests between HYMV antibodies and extracts of plants diseased by whitefly-transmitted agents in India such as A. conyzoides yellow mosaic, okra yellow vein mosaic, C. bonplandianus, yellow vein mosaic, M. coromandalianum yellow vein mosaic, tomato leaf curl and cassava mosaic. HYMV was also not found to be related serologically to bean golden mosaic, virus.