Apple blister mite (Eriophyes mali Nal): pest biology and measures to prevent it harmfulness on apple orchards in Ukraine
Authors: Yanovskyi Yu. , Sukhanov S. , Krykunov I. , Bandura L. , Fomenko O. 
Published: January 2022

Goal. To clarify the biological features of apple blister mite (Eriophyes mali Nal) and to investigate an efficacy of the insecticides Sivanto Prime 200 SL (flupiradifuran, 200 g/l), Danadim Stable, EC (dimethoat, 400 g/l), Oberon Rapid 240 SC, (spiromezifen, 228,6 g/l + abemektin, 11,4 g/l), Fufanon 570, EC (malathion, 570 g/l) and Aktofit, EC (aversektin С, 0,2%) on a reduction of a number and a harmfulness of apple blister mite (Eriophyes mali Nal), it impact on yields in commercial apple orchards.

Methods. Trials were conducted in farms of the Steppe (Zaporizhia, Dnipro, Kherson, Mykolaiv regions) and the Forest-Steppe zone of Ukraine (Chernivtsi, Vinnytsia, Cherkasy, Poltava, Kyiv regions). Detailed examinations of trees (spring, summer and autumn period) were carried out to determine the pests species presence, it number, infestation area, and in particular apple blister mite. The Laboratory studies of pest biology were carried out under the conditions of educational production department of Uman National University of Horticulture. For that purposes were used an entomological gardens, where were located cups with water and apple shoots, Hani Crisp variety. It shoots were cut in the industrial garden in the phase of «End of leaf bud swelling» (BBCH 03). A field method, in the commercial apple orchards. A type of apple variety trees was Hani Crisp. Planting scheme — 4.0 × 3.0 m. Year of planting — 1992. Crown shape — sparsely (improved) — tiered. Rootstock — MM-106. Phases of plant development at application timing — «More leaves unfolded, not yet at full size» (BBCH 15) — «Pink bud stage» (BBCH 57) and «Flowers fading «(BBCH 69). Soil — shallow, low — humus dusty — loamy podzolic leached black soils: humus content — 1.3—2.5%; pH 4.8 — 5.2; mobile compounds Р2О5 — 130—180 mg/kg and К2О — 8.9—9.2 mg/kg (by Chirikov method). The measures for care of the experimental site — loosening a soil in the stem strips during the growing period, an application of organic and mineral fertilizers, a pruning, a splaying of grass between the rows (row spacing),a protection from pests and diseases. The technical effectiveness of applications was determined in different rates against Apple blister mite and it impact on yields in commercial apple orchards. Calculations were made according to generally accepted methods in in horticulture, plant protection and entomology.

Results. It was established that the apple blister mite, which overwinters behind the scales of buds, begins it migration in spring at a midday air temperature above 10°C, massively infesting young leaves of trees in phases at application timing — «More leaves unfolded, not yet at full size «(BBCH 15) — «Pink bud stage» (BBCH 57), where it feeds up to 15 days, and afterthat in the formed gales during 18—23 days. It develops in two generations during the growing season The application of insecticides Sivanto Prime 200 SL (flupiradifuran, 200 g/l), Danadim Stable, EC (dimethoat, 400 g/l), Oberon Rapid 240 SC, (spiromezifen, 228,6 g/l + abemektin, 11.4 g/l), Fufanon 570, EC (malathion, 570 g/l) and Aktofit, EC (aversektin С, 0.2%) on a reduction of this species number of 72.9—93.3%. It allowed to obtain a high — grade apple product with a yield of 1.1—1.2 times higher comparing to control. The outcome of non-standard products did not exceed 11.7% compare to 18.3% in the control (water treatment). An application of these insecticides allowed to increase the effectiveness of main biometric indicators of trees, namely: the average length of annual shoots, shoot thickness, leaf surface area by 2.2—20.0%, 2.4—16.7% 1.02 times and 4.6—45.9%, accordingly, which is important for settlement of potential fruit buds and future yields. An analyze outcome of fruits biochemical analysis indicates about the feasibility of using these insecticides: versus to the control variant (water treatment) there is a higher percentage of solids content 0.8—2.3%, sugar — by 0.7—2.9%, tittric acids — by 1.8—3.5%, pectin substances — by 12.5%, and ascorbic acid — by 0.8—1.6%.

Conclusions. Apple blister mite overwinters behind the scales of buds and begins it migration in spring at a midday air temperature above 10°C, massively infesting young leaves of trees in phases at application timing — «More leaves unfolded, not yet at full size «(BBCH 15), «Pink bud stage» (BBCH 57), where it feeds up to 15 days, and afterthat in the formed gales during 18—23 days. It develops in two generations during the growing season The use of insecticides Sivanto Prime 200 SL (flupiradifuran, 200 g/l), Danadim Stable, EC (dimethoat, 400 g/l), Oberon Rapid 240 SC, (spiromezifen, 228.6 g/l + abemektin, 11.4 g/l), Fufanon 570, EC (malathion, 570 g/l) and Aktofit, EC (aversektin С, 0.2%) on a reduction allows to reduce harmfulness of apple blister mite in apple orchards and control its number during the growing period. A limitation of a number of the current pest in apple orchard by using the studied applications provided a yield increase and a marketable quality of the obtained fruit products and the effectiveness of basic biometric indicators of trees, namely: the average length of annual shoots, shoot thickness, leaf surface area, which is important for the potential yields in commercial apple orchards in the next years. During the growing season, taking into consideration technical efficacy, economic feasibility and the list of controlled harmful objects, the most feasible to control apple blister mite is treatment with Danadim Stable, EC (dimethoat, 400 g/l) and Fufanon 570, EC (malathion, 570 g/l) Considering the peculiarities of apple tree biology development (the phase duration «More leaves unfolded, not yet at full size» (BBCH 15) — no longer than 10 days and («Pink bud stage» (BBCH 57) — no longer than 5 days), peculiarities of pest biology in the phase («more leaves unfolded, not yet at full size «(BBCH 15) it locates openly on the young leaves and starting from the phase («Pink bud stage» (BBCH 57) already concentrated in new emerging scales) and peculiarities of insecticid — acaracides protection products against this pest and others phytophagys, during this period of vegetation it is highly needed to use in phase «More leaves unfolded, not yet at full size «(BBCH 15) Danadim Stable, EC (2,0 l/ha), and in the phase («Pink bud stage» (BBCH 57) — Fufanon 570, EC (2.0 l/ ha). After phase «Flowers fading» (BBCH 69) to control apple blister mite and other pests it is recommended to apply Danadim Stable, EC (2.0 l/ha).