The Pacific Pest List Database for agricultural trade facilitation

The Pest List Database for the Pacific is a user-friendly database that provides information on agricultural pest occurrences within a country as required to facilitate trade in terms of the International Plant Protection Convention and International Standards For Phytosanitary Measures. Its main outputs are: (a) a pest list for any specified crop intended for export and (b) a list of pest incursions detected on imported goods from any selected country. The system is designed for use by the 22 Pacific Island countries and territories that the Secretariat of the Pacific Community serves and is so far installed in five countries with a new one being delivered every 3–4 months. It is typically delivered with a few thousand known pest occurrence records of that country, and look-up lists of several thousand Pacific pests and a few hundred crops.     

Viruses in the northern potato-producing regions of Saudi Arabia

Agar double diffusion tests and, later, ELISAs were used to detect viruses associated with potato in 242 samples collected in 16 trips to Tabuk and Hail, northern regions of Saudi Arabia, in four consecutive growing seasons (autumn 1989, spring and autumn 1990 and spring 1991). Eleven different viruses were detected in Tabuk and 12 in Hail. The viruses detected in Tabuk were alfalfa mosaic (AMV), cucumber mosaic (CMV), tobacco mosaic (TMV), potato leaf roll (PLRV), tomato spotted wilt (TSWV), tobacco ringspot (TRSV) and potato A, M, S, X and Y. The same viruses, plus potato yellow dwarf (PYDV), were detected in Hail. AMV was most frequently and CMV least frequently detected in Tabuk, whereas in Hail the most and least common were PVA and PLRV respectively.     

Development of a powder formulation of Pseudomonas fluorescens for control of rice blast

Pseudomonas fluorescens strain Pf1, inhibitory to the growth of the rice blast pathogen Pyricularia oryzae in vitro , was developed as a talc-based powder formulation. When rice seeds were treated with this formulation, the bacteria spread to roots, stems and leaves of the plants and protected against leaf infection by P. oryzae . When applied as a foliar spray, the bacteria survived on the leaves. The powder formulation controlled leaf blast under greenhouse conditions. In tests as a seed treatment and foliar spray in four field trials it effectively controlled the disease and increased grain yield.     

The effect of solar heating of soil on natural and inoculated agrobacteria

Solarization trials were carried out over 3 years and in two countries to control crown gall disease on fruit trees and eliminate Agrobacterium . In 1992, agrobacteria in naturally infested soils of two Italian nurseries were monitored before and after solarization. Agrobacteria populations decreased by 99% and 92% after the treatment; however, crown gall incidence did not decrease. In 1993 and 1994 solarization was tested in Oregon in fields artificially infested with two marked strains of A. tumefaciens . In sandy loam soil, the target bacteria were eliminated in 4 weeks, while in silty clay soil the populations were markedly reduced after 2 months of treatment. Crown gall incidence on cherry rootstocks transplanted to the field at the end of 1993 was 3.7% in the sandy loam soil control plots, while no tumours were observed on plants from solarized plots. The use of solarization in combination with reduced doses of metham-sodium was also evaluated.     

Short-distance wind dispersal of the fungal pathogens causing Sigatoka diseases in banana and plantain

Airborne spores of the fungal pathogens causing Sigatoka diseases in banana and plantain were monitored using rotorod spore traps, sited at various heights within an infected plantation in Costa Rica from December 1993 to February 1994. Different capture patterns of ascospores and conidia were found and the relationship between wind behaviour and spore catches was investigated. This information has enabled an assessment to be made of the reliability of point measurements of airborne spores for monitoring spore movements on the plantation scale. The use of such information in forecasting the airborne movement of these spores and the likely role of the wind in the spread of this disease to uninfected areas is discussed.     

Role of acquisition and inoculation time in the expression of clonal variation for BYDV-PAV transmission in the aphid species Rhopalosiphum padi

Vector efficiency of 20 Rhopalosiphum padi clones, originating from Europe, North America and North Africa and exhibiting different types of life cycle, was evaluated by transmitting a French BYDV-PAV isolate to barley plants under five different acquisition/inoculation sequences (AAP/IAP). Differences between clones in transmission efficiency were found only when a short AAP was followed by a long IAP (6 h/120 h) and, to some extent, when a long AAP (48 h) was followed by a short IAP (6 h), but no differences were found when the conditions for virus transmission were optimal, i.e. long AAP followed by long IAP (48 h/120 h). There were no differences in transmission rates by clones of different geographical origins and with different life cycles. As a consequence, clonal variation is probably of little importance in the vector aspects of the epidemiology of PAV serotypes transmitted by R. padi , but the availability of a range of clones exhibiting transmission differences under limiting AAP or IAP conditions could be of interest for studies of virus–vector relationships.