Calonectria ilicicola, Gliocladiopsis sp. and Ilyonectria liriodendri were isolated from diseased roots of young avocado trees. Pathogenicity studies with seedlings of three avocado cultivars, Velvick, Hass and Reed, demonstrated that Calonectria ilicicola is a severe root rot pathogen, reducing the biomass of healthy roots, and reducing plant height over time. Calonectria ilicicola was re-isolated from diseased roots. Ilyonectria liriodendri and Gliocladiopsis sp. were not pathogenic and plant height was increased after Gliocladiopsis sp. amendment compared to all other treatments in trials with cvs Velvick and Hass.

Avocado trees (cv. Fuerte) were protected from root rot caused by Phytophthora cinnamomi by foliar metalaxyl. Protected trees had higher xylem water sprays with phosethyl-A1 or soil applications of potentials and showed faster and more complete recovery from water stress during the evening than un treated root rot affected trees. protected trees had greater fruit yields and there was a correlation between the incidence of the physiological disorder ring neck and xylem water potential in trees.

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Abstract.A detailed description and illustration of the Australian specimens of Peronospora lamii on Salvia spp. and on Lamium amplexicaule (Lamiaceae) are given.

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Root and heart rot diseases of pineapples and root rot of avocado caused by P. cinnamomi were controlled with fungicides. In pineapples, treatments were applied at planting and again after one and two months. Ridomil (0.8 kg a.i. ha-1) and Aliette (8 kg a.i. ha-1) controlled P. cinnamomi better than the standard Difolatan treatment (11 kg a.i. ha-1). In avocado nursery plants, Ridomil mixed with the soil before planting (1 g a.i. per 10 l soil) or drenched onto the soil surface around established plants (1 g a.i, per 10 1 container) controlled root rot for at least four months after treatment. Two applications of Ridomil, applied at a rate of 5 g a.i. m-2 as a soil drench beneath the canopy of 7 year old trees affected by root rot, controlled P. cinnamomi without affecting its biological antagonists and permitted trees to recover over a 12-month period.