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Grafting has the potential to improve melon fruit yield and quality, but it is currently held that a lack of compatibility between the rootstock and scion compromises such an effect. To throw light on this subject, we studied melon-pumpkin graft combinations with different levels of compatibility to assess to the effect of the rootstock identity on melon fruit yield and quality, including total fruit orthodiphenols, total flavonoids, and primary fruit metabolites. Melon cv. 'Kiran' (Ki) was grafted onto three pumpkin rootstocks, 'TZ-148' (TZ), 'Shimshon' (Sh), and '53006' (r53), characterized by high, moderate, and low compatibility, respectively. The non-grafted melon cultivar Ki was used as the control. The incompatible combination Ki/r53 gave the lowest fruit yield and the lowest average fruit weight. In that combination, the content of total ortho-diphenols increased vs. Ki and Ki/TZ and that of total flavonoids decreased vs. Ki/Sh. In addition, concentrations of the amino acids, glutamate, methionine, valine, alanine, glycine, and serine, increased in the pulp of the two compatible combinations, i.e., Ki/TZ and Ki/Sh, suggesting that rootstock identity and compatibility with melon Ki scion modulated amino acid synthesis. Our results show an association between rootstock identity (and level of compatibility with the scion) and an enhancement of fruit nutritional values, i.e., high concentrations of organic acids (determined as citrate, malate, fumarate, and succinate) and soluble carbohydrates (sucrose) were recorded in the pulp of the two compatible combinations, i.e., Ki/TZ and Ki/Sh. [ABSTRACT FROM AUTHOR]

Black mould, caused by Aspergillus niger, is the main fungal disease affecting date fruits. Symptoms develop inside the fruit, at the inner space between the pulp and the seed. This study focuses on the aetiology of black mould disease in Medjoul fruit. We followed symptom appearance naturally and after artificial A. niger inoculation at different development and maturity stages. Symptoms developed in only a short period during early fruit ripening. However, fruits were commonly colonized at earlier stages of development. Artificial inoculation of flowers and setting fruitlets increased the level of fruit colonization, while fungicide spraying at these stages decreased colonization. Several weeks following flower inoculation by A. niger, mycelium could be detected on degenerating stigmas and carpels as well as between the fruit and the calyx. Following inoculation with an A. niger strain expressing green fluorescent protein (A. nigerGFP), the pathogen was detected on stigmas of setting fruitlets but not within the stigmatic tissue or the transmitting tract of the carpel. The A. nigerGFP strain was detected during fruit development below the base of the large fruitlets and above the calyx surrounding the vascular bundle leading into the fruit. The results suggest that A. niger can infect and colonize flowers and setting fruitlets, grows on the degenerating carpels, and remains latent at a protected site at the base of the fruit until ripening. It then induces the typical black mould symptoms. The significance of these results for developing means to cope with the disease is discussed. [ABSTRACT FROM AUTHOR]

In 2000, a severe outbreak of phytoplasma-caused disease in Limonium spp. flowers devastated the industry in Israel; insecticides were not able to knock down and kill leafhopper vectors before they could transmit the pathogen. Nonchoice laboratory studies were conducted to determine the effect of UV-absorbing plastics on the movement of leafhoppers toward light; UV-absorbing plastic significantly reduced leafhopper movement. In choice trials conducted in sunlight, significantly more leafhoppers moved into the cage covered with regular plastic as opposed to the cage covered with UV-absorbing plastic. Field studies were conducted to determine at what height leafhoppers enter 2.5-3-m high walk-in tunnels; the majority enter the tunnels low to the ground, up to 1 m. Finally, field studies were conduced to compare leafhopper population levels in walk-in tunnels covered with UV-absorbing plastic or screening, and with ventilation holes at different heights above the ground. Elevated ventilation holes and UV-absorbing tunnel covering significantly reduced Orosius orientalis entrance into tunnels. Ramifications of these finding for leafhopper control are discussed. [ABSTRACT FROM AUTHOR]

The nematicidal activities of ammonium hydroxide, chitin and cottonseed meal applied to soil were enhanced by nitrapyrin, a nitrification inhibitor, in pot experiments. In a field trial, root galling index of tomato plants grown in the soil treated with 250 kg NH[sub 4]OH-N/ha in combination with nitrapyrin was lower than that of tomato plants grown without nitrapyrin 40 days after planting; however, there was no difference between these treatments in tomato yields and root galling indices at the end of the experiment (128 days). Nitrapyrin inhibited the nitrification of the ammonium added to the soil or released from cottonseed meal for up to 28 days, and kept ammonium concentrations and soil pH values higher for longer periods compared with those in soils treated without nitrapyrin. It is suggested that higher ammonia (NH[sub 3]) concentrations due to high soil pH and ammonium concentrations in the soil for longer periods caused the enhancement of nematicidal activities by nitrapyrin. The use of ammonia-releasing compounds in combination with a nitrification inhibitor may make nematode control more feasible by reducing the amount of amendments applied. [ABSTRACT FROM AUTHOR]

The nematicidal activities of ammonia-releasing and ammonium compounds were tested against the root-knot nematode Meloidogyne javanica in pot, microplot and field experiments. Among ten compounds tested, NH[sub 4]OH, (NH[sub 4])[sub 2]HPO[sub 4] and NH[sub 4]HCO[sub 3] showed greatest nematicidal activity at concentrations of 300 mg N/kg of NH[sub 4] or NH[sub 2] in pots. NH[sub 4]OH was found to be the most nematicidal of these compounds. Enclosure of pots containing NH[sub 4]OH-treated soils in plastic bags reduced the concentration of NH[sub 4]OH needed to kill the nematodes from 200 mg N/kg in open pots to only 75 mg N/kg. In a microplot experiment, treatment of nematode-infested soil with NH[sub 4]OH at 70 mg N/kg reduced the root-galling index to 0. In one field experiment, the nematicidal efficacy of NH[sub 4]OH on tomato plants at doses of 1000 and 2000 kg N/ha was equivalent to those of Telopic C35[sup ®] or metham sodium in combination with cadusafos. In another field experiment, NH[sub 4]OH at 500 and 1000 kg N/ha increased tomato yield and at 1000 kg N/ha reduced the galling index, compared with untreated controls. The results suggest that NH[sub 4]OH may serve as a nematicide in alkaline sandy soils. [ABSTRACT FROM AUTHOR]