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Symptoms typical of a phytoplasma infection were observed on a large number of Limonium hybrids in Israel in October 2000. Phytoplasma infection was confirmed by electron microscopy and polymerase chain reaction analysis. To identify the agent of pathogen spread surveys were made of candidate leafhoppers vectors in Limonium hybrid crops: one known phytoplasma vector (Orosius orientalis (Matsumura)) was present in very large numbers, ≈10-fold greater than any other species; three other known vectors were present in low to moderate numbers (Circulifer haematoceps complex (Mulsant et Rey), C. tenellus complex (Baker) and Exitianus capicola Stål); individual specimens of other vectors were occasionally found. Field collected specimens of these four species were shown to vector phytoplasma to healthy Limonium hybrid seedlings; this is the first time E. capicola has been shown to be a phytoplasma vector. A laboratory colony of O. orientalis was additionally shown to be able to acquire the phytoplasma from infected Limonium hybrids and subsequently vector it to healthy seedlings.
Melon plants grafted on Cucurbita rootstock may suffer from nutritional deficiencies due to reduced absorption and translocation of minerals to the foliage. Melon (Cucumis melo L.) cv. 6023 was grafted onto two interspecific Cucurbita rootstocks (Cucurbita maxima × Cucurbita moschata) ‘TZ-148’ and ‘Gad’. Nongrafted melons were used as controls. Two fertilization field experiments were conducted in walk-in tunnels in the northern Arava valley of southern Israel. Two fertigation regimes were used: 1) standard and 2) enriched for magnesium (Mg; 150 mg·L−1), manganese (Mn; 7.5 mg·L−1), and zinc (Zn; 0.75 mg·L−1) to increase the concentrations of the lacking elements. The enriched fertigation significantly increased Mn, Zn, and Mg contents in the leaf tissue. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), chloride (Cl), iron (Fe), and boron (B) were unaffected by the enriched fertilizer. There were no deficiency symptoms in grafted plants supplied with the enriched fertilizer.