Biological control ofBotrytis cinerea on tomato stem wounds withTrichoderma harzianum

The effectiveness ofTrichoderma harzianum in suppression of tomato stem rot caused byBotrytis cinerea was examined on tomato stem pieces and on whole plants. Ten days after simultanous inoculation withB. cinerea andT. harzianum, the incidence of infected stem pieces was reduced by 62–84%, the severity of infection by 68–71% and the intensity of sporulation by 87%. Seventeen days after inoculation of wounds on whole plants, the incidence of stem rot was reduced by 50 and 33% at 15 and 26 °C, respectively, and the incidence of rot at leaf scar sites on the main stem was reduced by 60 and 50%, respectively. Simultanous inoculation and pre-inoculation withT. harzianum gave good control ofB. cinerea (50 and 90% disease reduction, 10 days after inoculation). The rate of rotting was not reduced by the biocontrol agent once infection was established. However, sporulation byB. cinerea was specifically reduced on these rotting stem pieces. Temperature had a greater effect than vapour pressure deficit (VPD) on the efficacy of biocontrol. Suppression ofB. cinerea incidence byT. harzianum on stem pieces was significant at 10 °C and higher temperatures up to 26 °C. Control of infection was significantly lower at a VPD of 1.3 kPa (60% reduction), than at VPD<1.06 kPa (90–100% control). Reductions in the severity of stem rotting and the sporulation intensity of grey mould were generally not affected by VPD in the range 0.59–1.06 kPa. Survival ofT. harzianum on stems was affected by both temperature and VPD and was greatest at 10 °C at a low VPD and at 26 ° C at a high VPD.     

A generalized staphylococcal scalded skin-like disease in lambs

An idiopathic disease involving skin and kidneys was seen in two Merino lambs from the same herd. A generalized skin exfoliation in association with acute renal failure were the most prominent clinical features. The condition resembled staphylococcal scalded-skin syndrome of man, and pure cultures of Staphylococcus aureus were isolated from the lesion. Acute renal failure was diagnosed by clinical, biochemical and histological criteria, and necropsy.     

Regulators of ethylene biosynthesis or activity as a tool for reducing susceptibility of host plant tissues to infection by Botrytis cinerea

Several compounds were tested for their ability to reduce development of grey mould on rose, tomato, pepper, eggplant, French bean andSenecio sp. Removal of ethylene from the atmosphere surrounding rose flowers, or leaves of tomato and pepper, by potassium permanganate, resulted in slower grey mould development. Inhibition of ethylene activity by 2,5-norbornadiene controlled disease on all crops but tomato. Carbon dioxide controlled grey mould on roses, but the potential for use of these agents is in doubt. Inhibitors of ethylene biosynthesis such as aminooxyacetic acid (AOA), cobalt ion, the uncoupler 2,4-dinitrophenol and the radical scavenger salicylic acid were differentially effective in controlling the disease in the various hosts. Fifty mM AOA reduced grey mould on rose flowers by up to 97% when flowers were partially aerated. AOA was not phytotoxic on the tested rose cvs Golden Times and Jaguar. Combinations of ethylene absorption, inhibition of ethylene activity and ethylene biosynthesis did not result in better control as compared with the disease reduction ability of the compounds alone, tested on the various hosts. Application of benzyladenine, which reduces the host responsiveness to ethylene, resulted in 39–99% grey mould reduction in rose flowers and in leaves of tomato andSenecio sp. but was not effective on pepper or eggplant. Manipulation of ethylene presence and of host plant susceptibility to grey mould is discussed.Contribution from The Agricultural Research Organization, Bet Dagan, Israel, No. 3270-E, 1991 series.     

Disease symptoms caused byBotrytis cinerea inRuscus hypoglossum plants and their control

Small spots are a newly-defined manifestation ofBotrytis cinerea infection on phylloclades of ruscus. The dark, water-soaked spots encircled by a faint halo, which are found on young phylloclades, become brown lesions later but do not grow in size. Control of all symptoms caused byB. cinerea on ruscus (Ruscus hypoglossum L.),i.e., phylloclade rot or restricted lesions, upper branch rot, and stem canker, was achieved by sprays of fenetrazole (alone), diethofencarb + carbendazim, vinclozolin (alone) or alternately by sprays of diethofencarb + carbendazim, polyoxin B, and polyoxin D. Delay of disease development was achieved by copper sulfate pentahydrate and by the spray adjuvant Nufilm at a high rate of application. Mixing vinclozolin with copper, fenetrazole, TMTD or Nufilm did not control disease better than vinclozolin or fenetrazole alone. Postharvest control of gray mold (up to 72% reduction) in mature branches stored at 18°C was achieved by some of the above mentioned fungicides and by dichloftuanid, tebuconazole (alone or mixed together), iprodione, polyoxin AL, and vinclozolin + TMTD. Measures designed to improve field control of Botrytis epidemics in ruscus are discussed.     

The involvement of ethylene and calcium in gray mold of pelargonium,ruscus, and rose plants

Leaves ofPelargonium domesticum andRuscus hypoglossum infected byBotrytis cinerea Pers., produced 12 and 1.5 nl ethylene/h/g, respectively, 34 days after inoculation; wounded or healthy leaves and phyloclades of them produced much lower amounts. When the fungus was grown on dead leaves it produced negligible amounts of the gas even when supplemented with methionine. Exogenous ethylene enhanced gray mold development in both hosts. Silver thiosulfate, aminooxyacetic acid (AOA) and aminoethoxyvinylglycine significantly inhibited disease development in pelargonium, and the latter two compounds inhibited ethylene production. AOA inhibited disease development and ethylene production in cut rose flowers; calcium ions inhibited disease development whereas the chelator EGTA [ethylene glycol bis-(β-aminoethyl ether)N,N,N′,N′-tetraacetic acid] enhanced it. Disease suppression by an excess of Ca²⁺ was correlated with repression of ethylene production by the flowers, whereas deficiency in Ca²⁺ increased disease severity. Publication of the Agricultural Research Organization. No. 2413-E, 1988 series.     

Mastitis caused by Yersinia pseudotuberculosis in Israeli dairy cattle and public health implications

Yersinia pseudotuberculosis was isolated from mastitis cases in nine dairy cows in Israel. Six cases occurred on one farm (three instances of two cows, 2 months apart) and three cases on one farm each. Seven cows suffered from clinical and two from subclinical mastitis. All but two of the cows were culled. The literature describing cases of bovine mastitis caused by Y. pseudotuberculosis is reviewed and the human public health implications are discussed.     

Comparison of Antagonists of Botrytis cinerea in Greenhouse-grown Cucumber and Tomato under Different Climatic Conditions

The efficacy of Trichoderma harzianum T39 and the yeasts Aureobasidium pullulans and Cryptococcus albidus against Botrytis cinerea in cucumber and tomato was compared with chemical control. Four experiments were conducted in cucumber grown under different climatic conditions in The Netherlands, and two experiments were done in tomato both in the Netherlands and in Israel. T. harzianum and A. pullulans showed the most consistent control of B. cinerea, reducing stem lesions and death of plants by 40–100% in most cases. Control of stem lesions and subsequent wilting was generally better than control of symptoms on fruits. In some cases, the biocontrol agents were more effective than the broad-spectrum fungicide tolylfluanid and the selective fungicide iprodione. The climatic conditions did not strongly influence the efficacy of the biocontrol agents, but regression analysis showed that high temperature during the day and high vapour pressure deficit during the night reduced biocontrol efficacy. From the results, prospects for biocontrol of B. cinerea in greenhouse vegetables appear good under a range of conditions.     

Clinical and microbiological study of an otitis media outbreak in calves in a dairy herd.

On a dairy farm, otitis media was diagnosed in 64 suckler calves (21.8%) during a study period of 2 years, and in 10 calves (3.4%) in the third year. The inflammation was unilateral in 63 and bilateral in 11 calves. The affected calves were dull, lacked appetite, were pyrexic and displayed drooping ear or ears and tilted heads with purulent discharge exuding from the external ear canal. Of the affected animals, 56 (87.5%) were aged between 3 and 8 weeks. Morbidity was higher during the calving season and during the autumn and winter months (October-December). Pasteurella haemolytica was isolated from 21 (32.8%), P. multocida from 20 (31.2%), Actinomyces pyogenes from 11 (17.2%) and Streptococcus pneumoniae from three (4.7%) of the clinically affected calves only during the first two study years. The exudate of the acute ear infections contained, in addition to Pasteurella spp., various bacteria and yeasts. Most of these bacteria were isolated from healthy ears as well, and are likely to be part of the normal ear flora. On the other hand most of the yeasts were isolated from otitic calves. After a short course of an appropriate treatment infections healed in all cases. Possible preventive measures are discussed.     

Spray treatments combined with climate modification for the management of Leveillula taurica in sweet pepper

The effects of several spray and climate treatments on Leveillula taurica were tested under controlled and commercial greenhouse conditions either alone or combined with a climate treatment. Ampelomyces quisqualis AQ10 inhibited the germination of conidia on leaves, but not on glass. Trichoderma harzianum T39 inhibited germination on both surfaces. Neither the examined biological control agents (BCAs) nor the two tested mineral oils (AddQ and JMS Stylet-Oil) affected the viability of conidia. Sulphur drastically limited the germination and viability of L. taurica. In experiments at 15–25°C, AQ10 alone reduced hyphal leaf colonisation at 25°C. T. harzianum T39 significantly reduced leaf colonisation at all temperatures but significantly reduced disease only at 20–25°C. The oils significantly reduced leaf colonisation and sulphur reduced both leaf colonisation and disease at all temperatures. Results were confirmed in an experimental greenhouse. In a field experiment, azoxystrobin, polyoxin AL, neem extract, and T39 were effective; sulphur was superior to them. Under severe epidemic conditions the disease had a negative impact on yield; late fungicide treatments at spring-time were found unnecessary. Chemical sprays applied in alternation was compared with the ‘friendly’ spray regime (alternation of Heliosoufre, T. harzianum T39 + JMS Stylet oil, A. quisqualis AQ10+AddQ oil and Neemgard) in two climates i.e. (i.) day warm climate and (ii.) regular (cool) day climate regimes. In the warm climate, there was no significant difference in the performance of the ‘friendly’ spray regime and the chemical spray regime. However, in the cooler climate, the ‘friendly’ spray programme was not as effective as the chemical spray programme. It was concluded that a change in the greenhouse climate may affect the development of powdery mildew and, at the same time, promote the activity of BCAs and render a pathogen more vulnerable to these control agents, allowing for better disease suppression.