The effect of local fungicides on conidial germination of Spilocaea oleagina in Palestine

Abstract

Olive leaf spot (OLS) disease or peacock disease is caused by the fungus Spilocaea oleagina, it is the most destructive disease on olive trees in most regions of Palestine. The disease is controlled by application of copper containing fungicides. Currently, there are more than 20 different fungicides sold in the Palestinian market. The efficacy of these fungicides was not tested on OLS in Palestine. The aim of this work was to test the efficacy of three major fungicides used against the disease. Fungicide solutions containing Fungran, Copper Antracol, and Kocide®101 were prepared by dissolving 0.5 g of each in 200 ml distilled water (DW) according to manufacturer instruction. Five leaves infected with OLS were soaked in each solution for 30 min. Control leaves were placed in 200 ml DW. Leaves were then placed in 9 cm petri dishes containing 3 ml DW to provide high humidity (> 85%). Each day, one leaf was removed, washed in DW and cut into one-cm2 pieces. Leaf pieces holding OLS conidia were printed on olive leaf extract agar media. Results showed that after 24h of fungicide treatment, Kocide®101 was the most effective fungicide followed by Copper Antracol and Fungran with percent conidial germination 2.08, 2.9 and 25.5%, respectively. Interestingly, Fungran efficacy after 48h (2.8% germination) was higher but not significantly different than Kocide®101 and Copper Antracol. This study showed that the efficacy of the three commonly used fungicides against OLS disease in Palestine diminished after four days of treatment. Further studies are needed to test the efficacy of these fungicides under field conditions for a better control planning of peacock disease in Palestine.

No- or Low-Content Copper Compounds for Controlling Venturia oleaginea, the Causal Agent of Olive Leaf Spot Disease

“…It is characterized by premature defoliation, twig dieback, and, when infections are very severe, reduced flowering and fruit set [5][6][7][8]. The pathogen can also attack the fruit, causing delayed ripening, decreased oil content and unacceptable blemishes on table olives [5,9]. There is scarce information on the effects of the disease on yield, and more knowledge on this aspect would be very useful.…”

NGS transcriptomic analysis uncovers the possible resistance mechanisms of olive to Spilocea oleagina leaf spot infection

“…On the fruit, when attacked, the fungus manifests itself with brownish spots several millimeters in diameter ( Miller, 1949 ; Lanza et al., 2017 ). Fruit infection affects ripening, negatively influences oil yield, and causes detrimental injuries to table olives ( Salman et al., 2014 ; Lanza et al., 2017 , Buonaurio et al., 2023 ). Many studies have investigated the role of fungal cutinases in the invasion of plant tissues by enzymatically degrading the cuticle (e. g. Martin and Juniper, 1970 ; Matsuda et al, 1998 ).…”

“…Currently, only the application of synthetic fungicides (containing copper) allows disease control in the field throughout olive-growing regions of the world (e.g., Teviotdale et al., 1989 ; Shabi et al., 1994 ; Obanor et al., 2008 ; Sistani et al., 2009 ; Salman et al., 2014 ). However, the application of chemicals is not desirable in relation to human and environmental health factors.…”