Effectiveness of Miravis Prime fungicide application in American cranberry plantations

R. I. Pleskacevich

The modern concept of horticulture development predetermines the widespread introduction of less common berry crops, which are distinguished by stable production and adaptive potential. Currently, there are about 100 hectares of commercial American cranberry plantations. The largest commercial plantations of the crop are located at OJSC "Polesskie Zhuraviny" in the Pinsk district – 83 hectares. The yield of the crop ranges from 5 to 30 t/ha and depends on growing conditions and cultivar characteristics (projected yield of cranberry check plots is 10 t/ha). Obtaining high yields of American cranberry is difficult due to its susceptibility to diseases. Based on monitoring of the phytosanitary situation in commercial plantations in 2005–2007, 22 pathogens of American cranberry diseases were identified, including fruit rots, due to which harvest losses can reach 38.0%.

When cultivating American cranberry as a perennial berry crop, the rapid growth of vegetative mass creates conditions in the plantations for increasing the infectious reserve of pathogens. The use of sprinkler irrigation systems and short-term flooding of check plots, as integral elements of the technology for this crop, contribute to the creation of a microclimate favorable for the development of phytopathogenic microorganisms.

In commercial plantation systems, plant protection of American cranberry against diseases is mainly based on the application of fungicides. In the cost structure for the protection of plantations of this crop, the cost of fungicides is the main item. The number of registered preparations for the protection of American cranberry includes six fungicides: Azofos, 50%, Skor, EC, 0.2 l/ha, Rayek, EC, 0.2 l/ha, Delan, WG, 0.5–0.7 kg/ha, Chorus, WDG, 0.2 kg/ha, Acrobat MC, WDG, 2.0 kg/ha; 83% of them are single-component preparations belonging to the class of inorganic compounds, DMI (triazoles), quinones, and anilinopyrimidines. Systematic application of active ingredients of single-component preparations can contribute to a decrease in sensitivity to them and the emergence of resistance.

In connection with the above, the purpose of this research was to study the effectiveness of a two-component combined fungicide from the class of carboxamides or succinate dehydrogenase inhibitors (SDHI) and phenylpyrroles in reducing the harmfulness of dominant diseases of the American cranberry.

Research methodology. In 2021, field experiments to evaluate the effectiveness of the fungicide Miravis Prime, SC were conducted in American cranberry plantations of OJSC "Polesskie Zhuraviny" in the Pinsk district, and in 2022 at the branch laboratory of introduction and technology of non-traditional berry plants of the Central Botanical Garden of the NAS of Belarus in the Gantsevichi district of the Brest region on the 'Stevens' cultivar. The age of the plantations is 21–22 years. The planting scheme for the American cranberry is 25×25 cm. Control — no treatment. The application rate of the working solution is 400 l/ha. The experiment replication is 6-fold (10 m2 per replication). Methods of applying the preparation: double spraying with the fungicide Miravis Prime, SC (pydiflumetofen, 150 g/l + fludioxonil, 250 g/l) at an application rate of 0.5 l/ha and a single spraying at an application rate of 0.75 l/ha in the crop protection system. In American cranberry plantations, the first spraying with the fungicide at the minimum application rate of 0.5 l/ha was carried out in the third decade of June (22.06.21, 24.06.22) during the "beginning of flowering" phenophase, the period of Monilinia oxycoccii Wor. conidia dispersal; the second (14.07.21, 21.07.22) during the "fruit set" phenophase, the period of Gibbera myrtilli (Cooke) Petr. ascospores and Godronia cassandra Peck conidia dispersal. In 2022, a variant with a single spraying of the fungicide Miravis Prime, SC at the maximum application rate of 0.75 l/ha, which was carried out during the "fruit set" phenophase, was added to the experiment scheme.

The study of the effectiveness of the fungicide was carried out using "Methodological guidelines for registration trials of fungicides in agriculture" (2007). The species identity of the microorganisms was confirmed as a result of microscopic and cultural-morphological analysis using relevant identification keys. Statistical data processing was performed using the data analysis package of Microsoft Excel software at a 95% significance level.

Results and their discussion. Based on monitoring of the phytosanitary situation in 2021–2022 in American cranberry plantations, it was established that the basis of the crop's pathogenic complex was pathogens of monilinia blight and godronia – the fungi M. oxycoccii and G. cassandra (prevalence up to 10.8% and 18.6%), as well as fruit rots – up to 12.8% of affected organs. Gibbera leaf spot codominated (prevalence up to 6.2%).

Monilinia blight, leaf spots (godronia, gibbera spot) and fruit rots are the main threats to the yield of American cranberry. They not only reduce berry harvest but also spoil their marketability during storage. Field trials on the 'Stevens' cultivar showed that timely treatments with the fungicide Miravis Prime, SC allow for reliably protecting plantings at all critical stages of the growing season.

• Application rate of Miravis Prime, SC — 0.5–0.75 l/ha
• Effectiveness against moniliosis — 90.7–92.3%
• Effectiveness against gibbera spot — 90.7–95.2%
• Effectiveness against godronia (with 2 treatments) — 81.7–89.5%

1. First application is carried out in the third ten-day period of June, at the first signs of monilial blight (browning of individual flowers).
2. Second application is carried out in the second to third ten-day periods of July, when the first signs of spotting appear on the leaves.

Protection of shoots from monilial blight during flowering

Flowering of the large-fruited cranberry usually takes place in the third ten-day period of June. During this period, hot and unstable weather, when average daily air temperatures exceed the climatic norm by 1.9–2.1 °C with precipitation within the normal range (20.4–21.5 mm), creates favorable conditions for the dispersal of spores of the monilial blight pathogen. The first signs of the disease in the form of browning of flowers appear on June 22 (in 2021) and June 24 (in 2022). This determines the timing of the first application of the fungicide Miravis Prime, SC with an application rate of 0.5 l/ha.

Timely spraying with the preparation Miravis Prime, SC stops the spread of the infection. On the treated plots, by the end of the first half of the growing season (30.06), symptoms of the disease were completely absent. At the same time, in the control without applications, the prevalence of monilial blight on shoots reached 2.5 % (in 2021) and 2.6 % (in 2022), and in the reference variant with difenoconazole, it was 0.1–0.5 %.

In the second ten-day period of July, the prevalence of monilial blight on shoots without application increased to 6.5–10.8 %. In the experimental variant using Miravis Prime, SC, this indicator did not exceed 1.0 %, whereas in the reference, the infection rate grew to 3.4 %. As a result, the biological efficacy of a single application of the preparation at a dose of 0.5 l/ha was 92.3–90.7 %.

Biological efficacy of a single application of the fungicide Miravis Prime, SC against diseases of large-fruited cranberry (field trial, cultivar Stevens, 2021–2022)

* Note: the control shows disease prevalence (%); for application variants — biological efficacy (%).

Control of godronia, gibbera leaf spot, and fruit rots

In the second half of the growing season, godronia and gibbera leaf spot develop on cranberry leaves, and rots develop on berries. Moderate July temperatures and precipitation contribute to the development of leaf spots. The first signs of leaf diseases are recorded in the second to third ten-day periods of July (14.07.21 and 21.07.22). At this time, the second application of the fungicide Miravis Prime, SC with an application rate of 0.5 l/ha is carried out on the plantations. In the conditions of 2022, a variant with a single application of the preparation at the maximum dosage of 0.75 l/ha was also included in the trial scheme.

In the first to second ten-day periods of September, regular precipitation triggers an increase in the prevalence of godronia. By the berry ripening period, it increases to 17.2 % (in 2021) and 18.6 % (in 2022) on untreated plots. A single application of Miravis Prime, SC at the minimum rate of 0.5 l/ha reduces the infection rate to 6.0–5.0 % (efficacy 65.1–73.1 %), and increasing the application rate to 0.75 l/ha — to 3.5 % (efficacy 81.2 %).

Against gibbera leaf spot, the preparation showed a consistently high result in all application variants. The infection rate by the end of the growing season did not exceed 0.5 % compared to 6.2 % in the control, and the biological efficacy was 90.7–95.2 % (in the reference — 1.0 % infection). The development of fruit rots, which directly cause harvest losses during picking and reduce quality during storage, was also significantly suppressed by the fungicide.

Biological efficacy of double application of the fungicide Miravis Prime, SC against diseases of large-fruited cranberry (field trial, cultivar Stevens, 2021–2022)

* Note: the control shows disease prevalence (%); for application variants — biological efficacy (%).

Biological efficacy against rots and leaf spots

In years with heavy September precipitation (112–145 % of the norm), fruit rots can destroy a significant part of the large-fruited cranberry harvest. The first signs of diseases appear in the first ten-day period of August, when berries are growing and beginning to color. Without fungicidal protection, the proportion of infected berries increases to 12.8–10.9 %. During the trial years (2021–2022), monilial blight of shoots with a prevalence of up to 10.8 % and godronia on leaves — up to 18.6 % — were also recorded on the plantations without application.

In the structure of pathogens causing fruit rot during the harvesting period, the following pathogens dominate:

• M. oxycocci (hard rot, prevalence up to 5.0 %);
• G. cassandrae (end rot, prevalence up to 6.0 %);
• Diaporthe sp. (viscid rot, prevalence up to 1.8 %).

For crop protection, treatments with the fungicide Miravis Prime, SC are effective. A single spraying during the fruit set period at an application rate of 0.75 l/ha reduces the overall prevalence of rots to a minimum of 2.5 %. A double application of the preparation at 0.5 l/ha keeps the percentage of fruit infection within the range of 5.0–3.4 %.

• Biological efficiency at an application rate of 0.75 l/ha (single) — 77.1 %
• Biological efficiency at an application rate of 0.5 l/ha (double) — 60.9–68.8 %
• Biological efficiency at an application rate of 0.5 l/ha (single) — 57.0–63.3 %
• Yield losses in the control without treatments — up to 12.8–10.9 %

Application schemes of the fungicide and economic effect

Treatments with the preparation Miravis Prime, SC allow for reliable control of a complex of cranberry diseases at different phases of the growing season. A single spraying at the beginning of flowering with an application rate of 0.5 l/ha reduces the infection of shoots by monilial blight by 92.3–90.7 %, of leaves by godronia — by 65.1–73.1 %, and by gibbera — by 90.7–91.9 %. A double application at the beginning of flowering and during the fruit set period (0.5 l/ha each) restrains the development of godronia on leaves by 89.5–81.7 %, and of gibbera leaf spot — by 92.6–95.2 %.

A single treatment during the fruit set period at an application rate of 0.75 l/ha limits the development of godronia and gibbera leaf spot on leaves by 81.2–95.2 %, which is comparable to the double application scheme. At the same time, maximum protection of fruits from rots is achieved.

1. For the double scheme: the first treatment at the beginning of flowering, the second — during the fruit set period with an application rate of 0.5 l/ha.
2. For the single scheme: treatment during the fruit set period with an application rate of 0.75 l/ha.

Economic efficiency of various protection schemes on American cranberry plantings (cultivar Stevens, 2022):

Pleskatsevich, R. I. Diseases of American cranberry and justification of its protection methods / R. I. Pleskatsevich, E. E. Berlinchik // Actual problems of immunity and protection of agricultural crops from diseases and pests: abstracts of reports of the International Scientific and Practical Conference, Odessa, Sept. 11-14, 2007 / Selection and Genetics Institute, Ukr. Acad. of Agrar. Sciences; ed. by O. V. Babayants. – Odessa, 2007. – pp. 69–70.

9. Caruso, Frank L. Compendium of blueberry and cranberry diseases / Frank L. Caruso, Donald C. Ramsdell. – St. Paul, MN, USA: Aps Press, 1995. – 87 p.

R. I. Pleskatsevich RUE «Institute of Plant Protection», Priluki, Minsk region

EFFICIENCY OF THE FUNGICIDE MIRAVIS PRIME,

SC ON LARGE CRANBERRY

Annotation. The paper deals with the results of the two-year research on the efficiency of a single and double application of the fungicide Miravis Prime, SC (pydiflumetofen, 150 g/l+fludioxonil, 250 g/l) to large cranberry against dominant diseases.

It was established that the incidence of monilial shoot blight on large cranberry was reduced by 92.3–90.7 % with a single application of Miravis Prime, SC at a rate of 0.5 l/ha at the beginning of flowering. The biological efficiency of a double application of the fungicide Miravis Prime, SC was the following: against leaf godronia – 89.5–81.7 %, gibber spot disease – 92.6–95.2 %, fruit rot – 60.9–68.8 %. A single treatment during the fruit formation period with Miravis Prime, SC at a rate of 0.75 l/ha restrained the prevalence of godronia and gibber spot disease on leaves by 81.2–95.2 %, fruit rot – by 77.1 %. The application of the fungicide Miravis Prime, SC to large cranberry contributed to maintaining the fruit yield at the level of

Key words: large cranberry, monilial shoot blight, godronia, gibber spot disease, fruit rots, pathogens, prevalence, fungicide, biological efficiency.