Інтегрований хімічний захист кукурудзи від фузаріозу початків в умовах правобережного лісостепу України

Анотація

INTEGRATED CHEMICAL MANAGEMENT OF FUSARIUM EAR ROT ON MAIZE IN THE RIGHTBANK FORRESTSTEPPE
ZONE OF UKRAINE

V.Y. Omeniuk, A.F. Antonenko

Fusarium ear rot is one of the most common diseases in most of maize Ukrainian regions. Disease infection, incidence and severity depends on various biotic and abiotic factors, monoculture, growing technologies violations, weather conditions, pests damage. Last years fusarium ear rot gained worldwide economic importance because of its negative impact on grain quality and quantity. The disease is caused by pathogens fungi complex from the genus Fusarium, causing considerable damage in the early grain and represent a serious threat to food security through contamination of grain with mycotoxins that are harmful for humans, farm animals and birds.

The effectiveness of disease control depends on many factors: the fungicide active ingredients, its application rates and terms, pathogen species or strain and its aggressiveness, resistance varieties and hybrids of different maturity groups, presence of pests as pathogen vectors, meteorological conditions. To date, the most effective method of corn protection against the disease is seed treatment and spraying with fungicides during the growing season.

Due to the high incidence of Fusarium in growing season and lack of immune hybrids there’s an extremely urgent need for protective measures, including chemical treatments, depending on the optimal phase for pathogen infection of maize. According to published data the most critical phase of plant to pathogen Fusarium infection is flowering period, when cob’s early silk coming out. Conidia are carried on silk by wind or by rain drops, germinate to infect silk and developing grains.

Fusarium promotes mass incidence of European corn borer (ECB), which is one of the most common pests on maize. In recent years, due to the significant increase in corn acreage, respectively, and significantly increased its numbers. In addition to direct damage ECB, damaging plants, creates favorable goal infection for pathogens penetration, including boil smut, Fusarium and other ears’ diseases. Yield losses from it in favorable conditions can reach 25% per year.

Disease monitoring of its severity on plants, conducted in the late stage of full ripeness showed that different terms of the fungicide Amistar Extra 280 application with 0,75 l/ha rate to control Fusarium ear rot of maize showed different biological effectiveness.

In hybrid Aurum disease severity on control variant was 26,1% and yield – 5,46 t/ha. The best variant was to the same hybrid with fungicide treatment 3 days before inoculation grain yield on which was higher than the control at 0,8 t/ha. And the Standard had the disease severity accounted for 12,8%, with 28.7% on control; the yield was 5,94 t/ha, what is 0,6 t/ha higher than the control. The worst variant was Aurum hybrid with fungicide treatment for 7 days after inoculation. The disease severity was 22,5% and the yield – 5,87 t/ha, which is 0,41 t/ha higher than the control. And the Standard hybrid data of yield and disease infestation was almost at control variant level under the same conditions.

On average biological effectiveness of fungicide 3, 5 and 7 days (before and after inoculation) exceeded in average control 52, 41 and 22% on hybrid Aurum and 51, 30 and 10% for Standard hybrid.

The experimental data show that fungicide Amistar Extra 280 application reduces the disease data in average on 15%. The best variant among the different timing fungicide treatment on Aurum and Standard hybrids was 3 days before inoculation, compared with a control variant reduced disease severity by 14.6 and 15.8%.

Therefore, the results may indicate the effectiveness of preventive spraying to protect the maize cobs from pathogens Fusarium ear rot infection and spreading.

To complete the data also need to consider the harmfulness of ECB as vectors of Fusarium and protection from it to reduce the disease severity degree.

Phytosanitary monitoring, conducted with maize cobs’ lesions by ECB caterpillars testified the high level of its harmfulness that depended on its density and plant phase. On control variants of various hybrids embodiments control the degree of ears damage by ECB and Fusarium ranged from 41 to 46% and between 21,6 and 28,1% respectively. This suggests a direct relationship of Fusarium symptoms growth with increasing of ears affection by ECB (correlation coefficient r = 0,975). The application of insecticide Borey with rate of 0,14 l/ha reduced development of ECB and Fusarium ear rot with the biological efficacy 30,2 – 49,1%.

Hybrids average yield data analysis showed the lowest ECB impact on hybrid Aurum (7,61 t/ha), and the biggest – on hybrid Standard (6,52 t/ha). Thus, the value of stored yield (from 0,88 to 1,32 t/ha) shows the effectiveness of insecticide treatment (Borey with rate of 0,14 l/ha) against ECB harmfulness on maize.