Fruits is a scientific journal for original articles and reviews on fruit crops in temperate, Mediterranean, subtropical and tropical regions

Sensitivity of monosporial isolates of V. inaequalis, originated from apple orchards previously exposed (commercial and experimental) and those originated from location where fungicides had never been used (wild type), to strobilurin fungicides kresoxim-methyl and trifloxistrobin was investigated in this study. The experiments were carried out in laboratory using in vitro and in vivo methods. Mycelia growth inhibition on PDA medium with kresoxim-methyl and trifloxistrobin was monitored and sensitivity parameters (EC50 values) were determined using probit analysis. The isolates sensitivity in vivo was tested on apple seedlings using inoculation method. The EC50 values were ranging from 0.066-2.033 and 0.011-0.323 µg mL(-1) for kresoxim-methyl and trifloxistrobin, respectively. The wild type of isolates showed a normal susceptibility to kresoxim-methyl and trifloxistrobin, while isolates originated from experimental and commercial orchard where those fungicides had been used extensively, showed significantly lower sensitivity to the both strobilurin fungicides. The isolate that showed the resistance to kresoxim-methyl and trifloxistrobin in vitro test, also showed reduced sensitivity in vivo test and could not been controlled satisfactory by fungicide concentrations that are commercially used, as well as by double higher, after apple seedlings inoculation.

This study investigated various protection programs to control the European cherry fruit fly, cherry brown rot, and cherry leaf spot on sour cherries. The effects of acetamiprid, spinetoram, dodine, boscalid, and pyraclostrobin, applied alone and in combination with sucrose, were determined using standard EPPO methods. Pesticide residues in the cherry fruit were analyzed using liquid chromatography coupled with mass spectrometry. The highest efficacy in controlling the European cherry fruit fly was achieved by applying acetamiprid twice and spinetoram three times during fruit ripening. Successful protection against brown rot was achieved with a single application of boscalid and pyraclostrobin with the addition of sucrose. Dodine in combination with boscalid and pyraclostrobin showed good efficacy in controlling cherry leaf spot, which increased with the addition of sucrose. Residues of spinetoram, boscalid, and pyraclostrobin were below the limit of quantification, while only acetamiprid and dodine residues were detected in the fruit samples, but these were well below the maximum residue levels. This study demonstrates that several alternative protection programs can successfully protect cherries against the European cherry fruit fly and diseases during the critical stage of fruit ripening, with residue levels below the prescribed maximum levels.

During 2019 and 2020, field experiments were performed on sweet pepper crops to determine the efficacy of chemical insecticides (lambda-cyhalothrin, flubendiamide), semi-synthetic (emamectin benzoate), and biological pesticide (azadirachtin) in controlling cotton bollworm (Helicoverpa armigera). The experiments were performed in a randomized complete block design with four replications according to the standard EPPO method at the site of Veliko Gradiste (Serbia). Flubendiamide was applied at a rate of 50 g/ha, lambda-cyhalothrin at a rate of 7.5 g/ha, emamectin benzoate at a rate of 375 g/ha, and azadirachtin at a rate of 0.75 g/ha. The intensity of the 2nd generation cotton bollworm infestation on sweet pepper at this locality was higher during 2020 compared to 2019. After performing two treatments for the 2nd generation, flubendiamide showed the highest efficacy, ranging from 92.42% (3 days after treatment - DAT, 2020) to 95.56% (9DAT, 2019). Lambda-cyhalothrin had a satisfactory efficacy in the range of 81.93% (9DAT, 2020) to 90.63% (3DAT, 2019), and emamectin benzoate showed similar efficacy from 80.72% (9DAT, 2020) to 90.63% (3DAT, 2019). Azadirachtin could gain a significant place as a botanical insecticide in integrated pest management programs for sweet pepper protection from H. armigera. However, it statistically showed a significantly lower efficacy than other insecticides (77.27%: 3DAT, 2020 to 86.67%: 9DAT, 2019).

Three-year field trials were conducted to examine the efficacy of insecticides of different modes of action in the control of green peach aphid (Myzus persicae Sulzer) on nectarines, at the localities of Smederevo and Topola in Serbia. Insecticides from the group of neonicotinoids exhibited high efficacy in the control of M. persicae. The efficacy of imidacloprid ranged between 92.09% and 99.86%, while the efficacy of thiamethoxam was between 53.95% and 94.15%. During the entire trial period, organophosphate insecticides exhibited very low efficacy in the control of green peach aphid. The efficacy of dimethoate was poor in each evaluation term, ranging between -0.41% and 20.60%, while the efficacy of chlorpyrifos was between -17.24% and 30.96%. Deltamethrin and lambda-cyhalothrin, from the group of pyrethroids, also exhibited poor efficacy, which ranged from -41.94 to 60.68% and from -39.68 to 35.38%, respectively. Pymetrozine had poor initial efficacy (54.13%), although it was very good at later evaluations (98.48% and 99.14%). Similarly, the initial efficacy of flonicamid was poor (66.01 – 69.38%), while it was high at later evaluations (95.96 – 99.88%). Sulfoxaflor, a novel compound from the group of sulfoximines, exhibited high efficacy in the control of the green peach aphid in all evaluation terms (90.17 – 99.95%). According to the results of this research, flonicamid, pymetrozine, sulfoxaflor and neonicotinoids can provide effective protection of nectarine trees against M. persicae while the use of organophosphates and pyrethroids is not justified due to their very poor efficacy.