This is the first ICRISAT Information Bulletin that deals with a virus disease of groundnut. Attention is focused on bud necrosis disease, caused by tomato spotted wilt virus, because of its economic significance on three continents. Epidemics build up rapidly with little warning and cause serious losses to growers. Protocols for purification and identification of the virus are given in detail. The symptoms of the disease in groundnut are illustrated. Procedures for a simple enzyme-linked immunosorbent assay for the detection of the virus are given. The identification of the vector insects—species of Thysanoptera (thrips)—is difficult, and is still to be fully resolved. But a key is provided as an aid in identifying seven thrips species that have been implicated as vectors of tomato spotted wilt virus on groundnut. The current situation concerning management of bud necrosis disease is outlined. Suitable insecticides, cultural practices, biological control, and host-plant resistance are discussed to assist crop protection and extension workers in formulating integrated management systems appropriate to their particular situations.

An RFLP linkage map of the potato is presented which comprises 304 loci derived from 230 DNA probes and one morphological marker (tuber skin color). The self-incompatibility locus of potato was mapped to chromosome I, which is homoeologous to tomato chromosome I. By mapping chromosome-specific tomato RFLP markers in potato and, vice versa, potato markers in tomato, the different potato and tomato RFLP maps were aligned to each other and the similarity of the potato and tomato genome was confirmed. The numbers given to the 12 potato chromosomes are now in accordance with the established tomato nomenclature. Comparisons between potato RFLP maps derived from different genetic backgrounds revealed conservation of marker order but differences in chromosome and total map length. In particular, significant reduction of map length was observed in interspecific compared to intraspecific crosses. The distribution of regions with distorted segregation ratios in the genome was analyzed for four potato parents. The most prominent distortion of recombination was found to be caused by the self-incompatibility locus.

Fusarium crown and root rot caused by Fusarium f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 10(6) spores/plant applied at seed sowing killed 70-83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels.

Thirteen isolates of Trichoderma spp. and a single isolate of Penicillium sp. capable to control tomato stem rot caused by Sclerotium rolfsii under lath house test were screened for antagonistic activity against S. rolfsii under field plot condition. All test fungi were cultured on autoclaved sorghum seeds and prepared in powder formulation by using diatomite as a carrier. Mixture of fungal powder preparation, rice bran and organic compost in the ratio of 1:5:25 by weight was applied around the basal stem of 68-day-old tomato plants grown in natural field plots. All treated and non-treated (control) plants were inoculated with S. rolfsii-colonized sorghum seeds supplemented with rice bran. Eleven isolates of Trichoderma spp. and a single isolate of Penicillium sp. significantly (P=o.05) reduced disease incidence as compared to the control. Surviving plants of eleven Trichoderma and single Penicillium treatments ranged from 26 to 63 percent over a control. Yields (fruit weight) of tomato plants treated with Trichoderma isolates T-21, T-23, T-31 and T-34 were significantly higher than the control.

Biological control of basal stem rot of tomato (Lycopersicon esculentum L.) caused by Sclerotium rolfsii in the field condition was conducted by using Chaetomium cupreum as a potential microantagonist. The experiment was done by using Randomized Complete Block Design with five replications. Using viable ascospores, crude extract of microantagonist and heat killed ascorspores of C. cupreum the disease percentage could be reduced significantly and was different when compared to the nontreated check. However, using PCNB as chemical control was more effective to control the disease than using microantagonist. The microantagonist treated one had plant growth parameters and yields as similar as chemical treated one.

The present paper reviews results of a series of the studies pertaining to ecology and control of bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis. The infection of this disease took place when a population density of the causal bacteria was more than 1000000 cfu/g of tomato leaves, while there was no disease under the density of less than 1000-10000 cfu/g. Occurrence of bacterial canker in tomato was severer in an open field than in a protected field from rainwater. It may be concluded that multiplication and dissemination of causal bacteria are augmented under a rainfall condition in an open field. This result suggests that the cultivation of tomato plants under plastic films to avoid rainfalls be one of the practical methods for controlling bacterial canker. The selective medium, SMCMM which was developed for isolating causal bacteria from plant materials or from soils. was useful for an ecological study of this disease, especially for checking a population density of causal bacterial. It was recognized that the ELISA method could be used for detection of C. m. ssp. michiganensis and for the rapid diagnosis of the disease

Bud necros is diseases caused by tomato spotted wilt virus(4) and is one of the most important disease of Groundnut. The incidence of the disease in Raichur(Karnataka) varied from 5 to 75 percent and the incidence was found to be more in rabi than kharif Season………….

Some studies were undertaken to identify the association of distribution pattern of photosynthetic assimilates with the phyllotaxis and vascular system in tomato plants. The vascular system of tomato consisted basically of four orthostichies with two vascular bundles from each leaf. It was clearly observed that the arrangement of the vascular system affected a distribution pattern of 14C-assimilates. The source leaves exported only a smaller portion of their assimilates to young leaves located on the opposite orthostichy to them, as compared with those on the same as well as side orthostichies. Since tomato plants have a sympodial branching system, the leaf which was situated just above the inflorescence differentiated in advance to the inflorescence. The vascular bundles of the leaf in a sympodial branch near inflorescence developed in the location between the inflorescence and the leaf just above it. This vascular pattern caused a limited distribution of photosynthetic assimilates to the inflorescence from the leaf just above it

Bacterial wilt in peanut has recently become increasingly important in Thailand, causing severe damages in a certain local cultivar grownh in some areas in the Central Plain. It also was found occasionally, although at a very low incidence, in Chaiyaphum province in the Northeast. These findings indicated the potential of this disease to become outbreak in major growing areas. Therefore, information on the nature of the disease, its etiology and epidemiology are deem necessary. It is widely known that tomato isolates of P. solanacearum can be found in almost any planting areas including those in the Northeast, but wilt in peanut has never been reported or rarely occurs in those areas. This indicates certain differences from the two isolate. In this study, their reactions on common hosts and serological reactions were investigated. When inoculated into Sida tomatoes, the tomato isolate Srichiangmai 11 (TS-11) caused a very severe symptom and subsequently the plants were killed. The peanut isolate Nakhon Sawan (PN-N) (Kindly contributed by the DOA) induced only systemic chlorosis, and the plants survived until fruiting. In contrast, when PN-N was inoculated to Khon Kaen 60-2 and Tainan 9 peanuts, the whole plants withered rapidly and were eventually killed. The TS-11 isolate, however, withered only the inoculated quadrifoliate or caused necrosis along midribs of some leaves and the plants recovered and appeared normal. An antiserum prepared from membrane protein complex (MPC) of TS-11 reacted only to the homologous isolate and other tomato isolates but not PN-N isolate when tested by DAC ELISA. The concentration of primary antiserum was 1:5000 in a conjugate buffer. When undiluted antiserum of TS-11 and other antisera against whole cells of various tomato isolates were used in gel double diffusion test, the antigens from peanut isolate appeared to give two precipitin bands to the antisera against isolates collected from Khon Kaen province (TNS-E and TKKU-B) but only one band was detected if reacted with anti TS-11 and T3204 isolates collected form Nong Kai.