Semillas de tomate de la variedad Rutgers fueron inoculadas con tres cepas de dos especies bacterianas antagónicas (Bacillus cereus y Pseudomonas pseudoalcaligenes) y colocadas sobre papel de filtro previamente inoculado con el hongo patógeno Fusarium oxysporum var. lycopersici. Se tomaron datos de germinaación, crecimiento del tallo y de la raíz, así como el peso seco y observaciones sobre los efectos que el patógeno causaba en las raííces de las plántulas. Los mejores resultados en la inhibición del efecto dañino causado por el hongo patógeno, fueron las Pseudomonas pseudoalcaligenes y la cepa C-3 de Bacillus cereus. | Rutgers tomato seeds were inoculated with two antagonic bacteria (Bacillus cereus and Pseudomonas pseudoalcaligenes) and put on sterilized filter paper which was previously inoculated with the soil borne patogen Fusarium oxysporum var. lycopersici. Germination, stalk and root growth, as well as dry weight data an observationes on the seedling roots by the patogen were recorded. Pseudomonas pseudoalcaligenes and C-3 strain of Bacillus cereus showed the best results on the inhibition of detrimental efects caused by the patogen fungus in seed and seedling tomato.

The phosphorus nutritional status of some plants has been shown to influence the plant's response to salinity. The objective of this study was to determine if this interaction influenced the plant's water relations, fixation of CO₂, and yield. Tomato (Lycopersicon esculentum Mill.) and wheat (Triticum aestivum L.) were grown to maturity in nutrient solution cultures containing low to excessive concentrations of NaCl and P. Leaf total water potential (ᴸψₜ) and its components, osmotic (ᴸψₒ) and pressure (ᴸψₚ), decreased for both crops as salinity levels increased. Increases in the P concentration tended to increase ᴸψₜ and ᴸψₒ but decrease ᴸψₚ, although the changes were not always consistent. Interactions between salinity and P treatments caused significant differences in ᴸψₜ and ᴸψₚ for wheat. Statistically significant multiple regression equations were developed for ᴸψₜ, ᴸψₒ, and ᴸψₚ as a function of NaCl and P concentrations for both crops. Plant yields were well-correlated with ᴸψₜ and ᴸψₒ, indicating that these measurements may provide a good characterization of salt stress. Measurements of leaf stomatal diffusion resistance to water vapor (rH₂O) and carbon dioxide (rCO₂) and calculated values of mesophyll resistance (rₘ) increased significantly as salinity increased for tomato. Although the resistance values for wheat also increased as salinity increased, only the rCO₂ measurements rose significantly. The significant increases in rCO₂ and rₘ for tomato with additions of salinity indicate a significant reduction in the rate of photosynthesis. Increasing P values consistently reduced the gaseous resistance levels although the reductions were not always statistically significant. There were no significant interactions between salinity and P treatments for any of these resistance measurements.

A drip irrigation system was used to irrigate single tomato plants, each grown in a thin layer of an inert root medium supported between two glass plates. Sodium chloride was added to the medium and, with irrigation, was distributed unevenly through the root medium. The lowest concentration occurred immediately below the dripper outlet, the highest at the edge of the wetting pattern. Different amounts of sodium chloride were added initially, and these resulted in different concentrations of salt at the edges of the wetting patterns.With increasing amounts of salt added to the system, root growth was restricted to smaller volumes of root-zone space immediately below the dripper outlet, where minimum salt concentrations occurred. The percentage root distribution was higher immediately below the dripper outlet with increasing salt loading of the root zone, but the weight of both roots and plant tops decreased with increasing salt.We infer from the results that an essential factor in the management of drip irrigation under saline conditions is to provide a large enough volume of wet soil with low salt concentration to minimize contact between roots and zones of high salinity. This should prevent growth depression caused by uptake of Na or Cl to toxic concentrations, osmotic effects, or restriction of the size of the root system.

One hundred and forty‐six tomato crops throughout England and Wales were assessed for diseases. The commonest fungus pathogen was Botrytis cinerea Pers. ex Fr. which caused stem lesions in 64 per cent of the crops, leaf lesions in 38 per cent and fruit ghost spot in 46 per cent. Benomyl tolerance was widespread in isolates of this pathogen and was detected in 50 of the 68 crops examined. Seventy‐seven per cent of isolates from crops sprayed with a methyl benzimidazole carbamate (MBC) fungicide were tolerant compared with 34 per cent from crops where these fungicides had not been used. Fulvia fulva (Cooke) Ciferri was found in 28 per cent of the crops but was severe in only three per cent. Didymella lycopersici Kleb. occurred in seven per cent of the crops. Tomato mosaic (TMV) symptoms were seen in 34 per cent of the crops, although 47 per cent of those surveyed were of resistant cultivars in which no virus symptoms were seen. The Dutch avirulent TMV strain MII‐16 was used for crop protection on 27 per cent of the nurseries. TMV strains collected from crops with symptoms were predominantly strain 1 (85 per cent) and 96 per cent of isolates from crops inoculated with MII‐16 were of this strain. No new strains or tobacco forms of TMV were found. Root rots were extremely common at the end of the crops, varying in intensity according to the pre‐planting soil treatment. Steam treatment was most effective (28 per cent root rot) with methyl bromide the next best (30 per cent), followed by dazomet (42 per cent). Methyl bromide was used by 45 per cent of growers, whereas 17 per cent used steam and 11 per cent dazomet. Peat‐bag culture was used on five per cent of the nurseries. In peat‐bag culture there was little root rot (11 per cent). Verticillium spp. were isolated from 25 per cent of crops in the survey and Fusarium oxysporum Schl. from eight per cent. Chimeras were found in 34 per cent of the crops, but only in 1.1 per cent of the affected plants was the chimera affecting the growing point and likely to affect yield. There was a tendency for early‐planted crops to have a greater incidence of chimera. Generally the cultural factors recorded did not appear to be connected with disease incidence, but there was a significant increase in the amount of Botrytis in the stopped plants. Benomyl, either as a spray or a drench, was the most commonly used fungicide, but more than a third of the crops did not receive any fungicidal treatments.