The effect of Meloidogyne ardenensis and three populations of M. hapla on the growth of tomato were compared at four temperatures. M. ardenensis caused greater plant height reduction at 15 than 18 deg C, the percent reduction was 27 and 20 respectively. Percent reduction in plant height caused by the American population M. hapla was 57, 43, 35 and 22 at 24, 21, 18 and 15 deg C respectively. The American and English populations of M. halpa were more damaging to tomato plants than the Canadian population and M. ardenensis. The American population was the only one which reproduced on tomato at all temperatures tested. M. ardenensis failed to produce at 21 and 24 deg C, the Canadian at 15 deg C and the English population at 15 and 18 deg C. At the higher densities (4,000 and 8,000 eggs), all the nematode species tested caused greater reduction in plant height, plant weight and root weights as compared to the control. The reproduction factor of the nematode species was negatively correlated with initial density.

Tomato spotted wilt virus (TSWV) was first reported in India in tomato in 1964 (Todd et dl., 1975). The occurrence of TSWV on a legume in ~India was first recorded in 1968 (Reddy et dl., 1968). The "bud necrosis disease" of groundnut, caused by TSWV, is now considered to be one of the most damaging groundnut diseases in India (Ghanekar et al., 1979a; Reddy, 1980). Bud necrosis is likely to have been present in India for some time although it has only recently become economically important. TSWV has also been reported on groundnuts in Brazil (Costa, 1941), the United States of America (Halliwell & Philley, 1974), South Africa (Klesser, 1966) and Australia (Helms et al., 1961). This chapter considers the epidemiology and control of bud necrosis and gives a brief account of other economically important diseases of legumes in India caused by TSWV.

Bud necrosis disease (BND), caused by tomato spotted wilt virus, is one of the most important virus diseases of groundnut in India. In order to ascertain the distribution and severity of BND in rabi (postrainy season) groundnut crops in the state of Andhra Pradesh surveys were undertaken in 10 major groundnut growing districts.

High molecular weight cell wall components from Phytophthora infestans caused "browning" in tomato callus, a decrease in survival of single tomato cells, and elicited antimicrobial activity compounds synthesis. Treated callus extracts inhibited germination of conidia, and reduced germ tube length and mycelial growth of Cladosporidium cucumerinum. Results were discussed for new knowledges in P. infestans. Tomato system and further possibilities for more thorough investigations on the kinetics and mechanism of phytoalexin in plant tissue cultures. | Sostanze di alto peso molecolare della parete cellulare, estratte da Phytophtora infestans, hanno causato l'imbrunimento di tessuti di callo di pomodoro ed una diminuizione della sopravvivenza di singole cellule in sospensione; hanno inoltre stimolato la sintesi di composti dotati di attivita antimicrobica. Gli estratti di calli trattati con tali sostanze hanno parzialmente inibito la germinazione dei conidi di Cladosporium cucumerium, riducendo anche l'allungamento del tubo germi nativo e la crescita del micelio.I risultati ottenuti portano un con tributo alla conosenza del sistema P.infestans-Pomodoro e aprono la possibilita di piu esaurienti studi sulla cinetica dei meccanismi di induzione delle fitoalessine nelle colture in vitro dei vegetali.