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Chemical Screening and Field Trials for Controlling Pitaya Flower Wet Rot Caused by Gilbertella persicaria
Effect of non-chemical materials on inhibition of (A) spore germination and (B) hyphae growth of <i>Gilbertella persicaria</i> isolates. The means shown here were the averaged values of the inhibition rates of the agents against F210187 and F212122 isolates. This experiment was conducted more than 2 times with 200 sporangial spores or 3 replicates of each isolate for each time [BDM: bordeaux mixture, NPA: neutralized phosphoric acid, LSM: line sulfur mixture, CNG (Active Power, TARI): 2.5% gallic acid, chinese nut-gall extract product, Cit-1 (Rust Escape, TARI): 20% citronella extract oil product 1, Cit-2 (Mold Stop, TARI): 10% citronella extract oil product 2, Cin-1 (Black Asura, TARI): 36% cinnamon extract oil microemulsifier 1, and Cin-2 (Anthracnose Escape, TARI): 40% cinnamon extract oil microemulsifier 2] (Bar = standard error).
Effect of non-chemical materials on inhibition of (A) spore germination and (B) hyphae growth of Gilbertella persicaria isolates. The means shown here were the averaged values of the inhibition rates of the agents against F210187 and F212122 isolates. This experiment was conducted more than 2 times with 200 sporangial spores or 3 replicates of each isolate for each time [BDM: bordeaux mixture, NPA: neutralized phosphoric acid, LSM: line sulfur mixture, CNG (Active Power, TARI): 2.5% gallic acid, chinese nut-gall extract product, Cit-1 (Rust Escape, TARI): 20% citronella extract oil product 1, Cit-2 (Mold Stop, TARI): 10% citronella extract oil product 2, Cin-1 (Black Asura, TARI): 36% cinnamon extract oil microemulsifier 1, and Cin-2 (Anthracnose Escape, TARI): 40% cinnamon extract oil microemulsifier 2] (Bar = standard error).

Author:Chu-Ping Lin, Jyh-Nong Tsai*, Ting-Fang Hsieh, and Pao-Jen Ann

Abstract:

    Pitaya Gilbertella rot, also called pitaya wet rot, is caused by Gilbertella persicaria. The pathogen not only damages the flowers and early fruit of pitaya (Hylocereus spp.) but also causes rot on mature fruit during storage. Because the disease has led to a huge amount of yield loss of pitaya in Taiwan, the objective of this study was to screen chemicals or eco-friendly agents for controlling this disease. A total of 27 synthetic chemicals and 10 eco-friendly agents were tested in vitro for the inhibition effect of mycelial growth and spore germination of G. persicaria. The results showed that among the tested synthetic chemicals, cyprodinil-fludioxonil mixture was the most effective chemical in inhibiting both spore germination and mycelial growth of the pathogen, and fluaziname was the best in inhibiting spore germination. As for eco-friendly agents, Black Asura (microemulsifier of cinnamon essential oil) and bordeaux mixture (mixture of lime and copper sulfate) were the most effective materials. Two field trials of disease control were conducted in a randomized complete block design in the summer of 2017 and 2018. In each experiment, the chemicals were sprayed 1–2 times on shoots and flowers of pitaya (Hylocereus undatus) during each flowering period. In 2017 field trial, the treatment of Black Asura and cyprodinil-fludioxonil mixture significantly lowered disease incidence of pitaya flower and young fruit wet rot (14.2% ± 6.2% and 14.5% ± 8.0%, respectively) when compared with the control (24.9% ± 7.0%) (P < 0.05). In 2018 field trial, the treatment of cyprodinil-fludioxonil mixture, as well as fluaziname, also showed effective in disease control (11.1% ± 2.3% and 11.8% ± 4.5%, respectively) when compared with the control (18.7% ± 1.3%) (P < 0.05). The above test results revealed that cyprodinil-fludioxonil mixture, fluaziname, and Black Asura are potential chemicals for the control of pitaya flower and young fruit wet rot in field.

Key words:Pitaya flower wet rot, Chemical control, Field trial

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Journal of
Taiwan Agricultural Research
Vol. 73, No.2 (2024) ISSN: 2790-086X Vol. 73, No.2 (2024)
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