Vera Sergeeva

Evidence of early flower infection in olives (Olea europaea) by Colletotrichum acutatum and C. gloeosporioides causing anthracnose disease

New evidence is provided for early asymptomatic infection of flowers of olive varieties Barnea and Manzanillo byColletotrichum acutatum andC. gloeosporioides. Asymptomatic infection of olive flowers by these species ofColletotrichum and the likely quiescent behaviour of the pathogens resulting in symptomatic disease expression of mature fruits has not been recorded anywhere previously.

Botryosphaeria stevensii infection of Pinot Noir grapevines by soil–root transmission

Botryosphaeria grapevine die-back is usually caused by infection of wounds in aerial parts of the grapevine. However, this study shows that Botryosphaeria stevensii infection can also be initiated from soilborne inoculum. Six months after soil inoculation with B. stevensii, shoots from two of six potted Pinot Noir vines were found to be infected with the fungus. This is the first report of infection grapevines by B. stevensii through soil-root transmission. Infection from soilborne inoculum has serious implications for vineyard replanting after removal of diseased vines.

Abiotic diseases of olive

SUMMARY Several non-parasitic diseases are of primary significance for olive trees growing in the Mediterranean area and other warm-temperate regions of the world. As for other crops, they are generally poorly understood and often completely unrecognized, especially in olive which is considered a crop of marginal lands. The origin may rest with a lack/excess of essential nutrients or an excess of non-essential elements; it may be an unsatisfactory environment: too cold or hot, too wet or dry, or too windy; there may be unsuitable soil characteristics such as poor physical condition, water-logging, salinity, improper pH, and so on. Also pollution in the environment, spray and fire damage, and climatic extremes like lightning, hail, and snow can cause heavy losses to olive. This review focuses on the most important disorders of olive caused by environmental, physical, and chemical stresses that can affect the normal physiological processes in trees. An integrated view is utilized to highlight interactions with plant healthiness, production, and quality.

First report of Colletotrichum acutatum and C. gloeosporioides causing leaf spots of olives (Olea europaea) in Australia

We report the occurrence ofColletotrichum acutatum andC. gloeosporioides on leaves of olives (Olea europaea) for the first time in Australia.

First report of anilinopyrimidine-resistant phenotypes in Botrytis cinerea on grapevines in Australia

Anilinopyrimidine-resistant phenotypes of Botrytis cinerea are recorded for the first time in Australian vineyards. The frequency of resistance among the 910 isolates obtained during 1997/98, 1999/2000 and 2000/01 was 0%, 12% and 4%, respectively. There were two resistant phenotypes and these were designated as low resistant (EC50=1.5 mg/L) and resistant (EC50=2.5 mg/L). Both the resistant phenotypes were found to possess multiple resistances to benomyl (benzimidazole) and iprodione (dicarboximide). It is considered that the frequency of anilinopyrimidine resistance observed currently in Australian vineyards does not pose any immediate risk in the use of pyrimethanil for management of Botrytis bunch rot.

Species of Pestalotiopsis and related genera occurring on grapevines in Australia

Descriptions of several appendage-bearing coelomycetes such as Pestalotiopsis and related genera occurring on grapevines in Australia are given. Species isolated included Pestalotiopsis uvicola, P. menezesiana, Seirnatosporium hysterioides, Truncatella angustata, and Sporocadus rhododendri. Infection studies showed that berries of grapevines were infected by P. uvicola more readily at later stages of berry development than at the earlier stages.

Germination of β conidia of Phomopsis viticola

Germination of β conidia of Phomopsis viticola was recorded in potato-dextrose liquid medium but not in sterile distilled water. Maximum germination of β conidia in vitro occurred within 144 h reaching a plateau around 60–80 h at 26°C, whereas α conidia germinated within 28 h at 30°C. Preliminary bioassays indicated that the β conidia are potentially capable of symptomless infection of grapevine leaves. However, further studies are required to confirm this.

The use of fluorochromes to determine the effect of chlorine dioxide on survival of Plasmopara viticola on grapevine

A technique using fluorochromes was developed to quantify the survival of Plasmopara viticola on the leaves of grapevine cv. Chardonnay following application of chlorine dioxide (ClO2). The staining combination of 5,6 carboxyfluorescein diacetate and propidium iodide produced intense green fluorescence of live conidia and red fluorescence of dead conidia of the fungal pathogen under blue excitation. The number of live conidia on the leaves emitting green fluorescence decreased significantly with increase in the concentration of ClO2. The percentage of dead conidia on leaves treated with 25 or 50 ppm of ClO2 were 38 and 99, respectively. No conidia survived on leaves treated with 100 ppm of ClO2. The bioassay can be applied to studies on screening fungicides for disease control. The advantages of the fluorochrome bioassay used in this study are that it is faster than measuring germination of conidia, and that it gives a quantitative estimate of survival of the pathogen.

Observations on spot caused by Fusicladium oleagineum on olives (Olea europaea) in New South Wales, Australia

The first record of peacock spot on olives in New South Wales, Australia, was made informally in 1947 but no herbarium specimen was deposited nor descriptions made. Subsequent descriptions of this disease in Australia have been sketchy and generally reported in extension articles for olive growers. We provide here a consolidated report and description of the occurrence of Fusicladium oleagineum on the lamina, veins and petioles of leaves, fruits and pedicels of fruits of olives (Olea europaea) in New South Wales.

First report of Macrophomina phaseolina on olives (Olea europaea) in Australia

Macrophomina phaseolina was isolated from diseased olive roots. This is the first record on this host in Australia. Infection studies demonstrated that two isolates of the fungus were capable of inducing typical charcoal rot symptoms on rooted olive cuttings.