In vitro effect of four fungicides on Colletotrichum gloeosporioides causing anthracnosis on the Red Globe grape variety

Abstract

Anthracnose is considered one of the most important diseases of grape crops. In this study, we evaluated the in vitro effect on potato dextrose agar (PDA) of four fungicides: benomyl (Benlate® 50 WP), carbendazim (Belico ® 500 SC), chlorothalonil (Odeon® 720 SC), and dodine (Syllit ® 400 SC) using three concentrations on a Colletotrichum gloeosporioides isolate. This species complex causes anthracnose on the Red Globe grape variety. The concentrations of each fungicide were: benomyl at 0.5, 0.25, and 1 g.L-1; carbendazim at 0.6, 0.3, and 1.2 mL.L-1; chlorothalonil at 2.4, 1.2, and 4.8 mL.L-1, and dodine at 1.6, 0.8, and 3.2 mL.L-1. Evaluated the inhibition of mycelial growth and the sporulation of the fungus. The fungus mycelium exposed to the commercial dose of the fungicides was observed using environmental scanning electron microscopy (ESEM). We used a completely randomized design with 13 treatments and five repetitions. Our results showed a degree of differential efficacy for the four fungicides and their effects were directly proportional to the dose used, benomyl and chlorothalonil being the most efficient in controlling the mycelial growth of the fungus. At the commercial dose, sporulation was inhibited at a higher rate by benomyl showing no statistically significant differences with the other products except chlorothalonil and dodine when the recommended dose was reduced by half. The damage observed by ESEM on the fungus mycelium ratified the effect obtained in vitro, i.e., deformed hyphae and irregular growth. The results of this study, complemented by electron microscopy, are promising for the appropriate selection of the best fungicides for controlling anthracnose on grape fruits, subject to the timely and correct diagnosis of the disease.

Modeling the Effects of the Environment and the Host Plant on the Ripe Rot of Grapes, Caused by the Colletotrichum Species

“…Because the control of ripe rot under these conditions is often ineffective and may result in fungicide residue problems [67], growers should prevent the disease through timely fungicide applications, from flowering to véraison. In this context, our model can contribute to the scheduling of fungicides based on the risk of infection rather than on the calendar; scheduling fungicides according to the risk of infection results in an effective control of the downy and powdery mildew of grapevines with less use of chemicals [20,21] and, as a consequence, in a reduced risk of resistance to fungicides in Colletotrichum populations [68][69][70][71].…”

Insights into Grape Ripe Rot: A Focus on the Colletotrichum gloeosporioides Species Complex and Its Management Strategies

“…In addition to the fungicides categorized under single-site chemistries, some fungicides used for grape disease management have multisite contact activity. Fungicides with multisite activity used for the management of grape ripe rot include oxine-copper, mancozeb, maneb, metiram, thiram, ziram, captan, captafol, folpet, chlorothalonil, iminoctadine, and dithianon [19,69,80,137,140]. In the study of Greer et al (2011) [6], C. acutatum exhibited a higher sensitivity to captan than C. gloeosporioides in Australia.…”

“…In the study of Greer et al (2011) [6], C. acutatum exhibited a higher sensitivity to captan than C. gloeosporioides in Australia. Recent in vitro studies have demonstrated that substances such as oxine-copper, mancozeb, metiram, thiram, chlorothalonil, iminoctadine, and dithianon effectively inhibit the grape isolates of the CGSC [80,140].…”