Abstract. Pseudocercospora macadamiae sp. nov. is described from diseased husks of plantation-grown Macadamia integrifolia in Queensland and northern New South Wales, Australia.

No abstract

No abstract

Treatments with a partially neutralized formulation of phosphorous acid containing potassium phosphite were assessed for control of Phytophthora diseases in subtropical and temperate crops in Australia. In Queensland, trunk injections of phosphite (10% solution) controlled severe root rot (Phytophthora cinnamomi) of avocado trees and resulted in the recovery of trees. Single pre‐harvest sprays (2.5 kg ha‐1) of phosphite controlled root and heart rot (P. cinnamomi) of pineapples. Foliar sprays of phosphite (64 g per tree) controlled root rot (P. nicotianae var. parasitica) and trunk canker (P. citrophthora) of mandarin trees. In Victoria, a foliar spray of phosphite (300 g ha‐1) reduced root rot (P. clandestina) of subterranean clover and increased dry matter by 1.96 to 5.11 t ha‐1. Trunk injections of phosphite (10% solution) controlled trunk rot (P. cactorum) of peach trees and foliar sprays (10 kg ha‐1) reduced severity of root rot (P. nicotianae var. nicotianae) of tomatoes.

SUMMARY Pseudomonas solanacearum biovar 3 was identified as the causal agent of two disease syndromes in custard apples (Annona spp.), namely sudden death of young trees and the decline of mature trees. Cross inoculation tests using cultures of P. solanacearum from custard apple and tomato on A. squamosa, A. squamosa×A. cherimola hybrids, Capsicum annuum, three cultivars of Lycopersicon esculentum and Solanum tuberosum failed to distinguish differences in virulence among these isolates. Bacterial wilt resistant rootstock clones, particularly of A. cherimola, constitute the most effective control measure available.