Physiologically reasonable protection of apple plants against scab

Modern systems of protection of fruit crops are based on phytosanitary monitoring, evidence-based selection of agents regarding resistant varieties, the physiological state of apple plants and weather conditions of a particular apple-growing season. Currently, the system of protecting orchards from pests is undergoing significant changes due to the increasing number of extreme weather conditions that weaken the fruit plants [1-3, 9], having a significant impact on the quantity and harmfulness of herbivores and plant pathogens.

Phytosanitary destabilization of gardening, which began in 1990, has been continuing for many years and entails periodic massive outbreaks of diseases and propagation of pests, typical of apple tree orchards. The most dangerous disease is the scab. We have also noted the formation of complex infections: scab + Phyllosticta leaf blight, scab + Alternaria blight [7, 8]. We noticed a sharp increase in harmfulness of Citospora after a harsh winter of 2005-2006. The disease is accompanied by bark dieback on tree bodies, main branches or their crutches. The resulting damage led to the death of individual trees or whole plantations and to negative consequences within the coming years, as some sections of branches were populated by basidiomycetes [4, 5].

Difficult conditions of 2009-2010 winter and extreme growing season of 2010 worsened the condition of apple trees, which were damaged during the winter of 2005-2006. Inadequate hydration for tissue maturing led to the development of diseases of the main branches and death of trees. In 2011 and especially in 2012 conditions were favorable for the restoration of damaged tissues, but it was not complete in 2011, as it was significantly affected by adverse effects of exposure to extreme stressors of 2010. Thus, the analysis of the functional state of plants in apple plantations of Tambov, Lipetsk, Voronezh and other regions showed that in 2010 average vegetation values ​​of photosynthetic activity of leaves were at 30-35% (depending on the variety and the orchard) below optimal, in 2011 – 15-20%, and only in 2012 the value was close to optimal. It should be noted that the maintenance of a high level of leaf protection is necessary even in a weakened condition of apple trees.

The maximum efficiency of the system of apple crops protection from disease is achieved by a scientifically based approach to its construction: the identification of the most dangerous diseases; year-round monitoring of weather conditions and the physiological state of plants; short-term forecast for the development of major diseases using technical means; selection of agents that are effective against a number of harmful objects, taking into account the variety stability, the physiological state of the apple trees and the weather conditions of a particular growing season; use of tank mixtures of systemic and contact (75% of normal consumption) fungicides in the fight against major diseases; alternation of preparations with different classes and mechanisms of action during growing; maintenance of plant resistance to adverse weather factors, pests through the use of spray dressings with macro- and micronutrients; holding pre-harvest fungicide treatment of apple trees to reduce the development of fungal diseases during storage.

Protective measures should lead to the simultaneous destruction of the entire complex of harmful organisms, with the timing and amount of pesticide treatments are determined by the most dangerous species.

Materials and methods

In 2006-2012 farms in Tambov (JSC "Dubovoye") and Lipetsk (JSC "Agronom") regions tested apple tree protection systems on varieties with different scab resistance: susceptible - Zhigulevskoye, Rossoshanskoye Striped, Lobo, Martovskoye; relatively stable - Bogatyr, Vishnevoye, Orlovskoye Striped.

Prototype system

Treatment of plants with preparations according to phonological phases

Green cone – felon herb - Cumulus DF, WDG + polyram DF, WDG, 4.0 + 2.5 kg / ha or delan WG + Cumulus DF, WDG, 0.6 + 3.0 kg / ha or kuproksat KS 5.0 kg / ha.

Inflorescence - rosebud: Cumulus DF, WDG + polyram DF, WDG, 4.0 + 2.5 kg / ha or delan WG + Cumulus DF, WDG, 0.6 + 4.0 kg / ha.

Beginning of flowering - tanks mixture of fungicides: Stroby, WDG + delan WG, 0.2 + 0.4 kg / ha, or Tercel (two-component fungicide), WDG (2.5 kg / ha).

End of flowering (fall of 75% petals): Stroby, WDG (0.2 kg / ha) or stroby, WDG + delan WG, 0.2 + 0.4 kg / ha or Tercel, WDG (2.5 kg / ha ). High temperatures of the growing season in 2007 made it possible to cancel the spraying at the end of flowering.

Hazelnut, delan WG, 0.6 kg / ha (in 2007 - stroby, WDG, 0.2 kg / ha).

Walnut: stroby, WDG + polyram DF, WDG, 0.2 + 1.5 kg / ha (2006); Delan WG 0.6 kg / ha (2007); Stroby, WDG+ delan, WG 0.2 + 0.4 kg / ha (2008-2009.); Tercel, WDG, 2.5 kg / ha, or Stroby, WDG + Cumulus DF, WDG, 0.2 + 3.0 kg / ha.

The growth and ripening of fruit: Cumulus DF, WDG + polyram DF, WDG, 3.0 + 2.0 kg / ha or polyram DF, WDG, 2.0 kg / ha or delan, WG, 0.6 kg / ha.

The economic system

The use of Preparations at different phonological phases

Green cone - felon herb: kuproksat, KS 5.0 kg / ha; or Abiga-peak, VS, 5.0 kg/ha.

Nomination of inflorescence - rosebud: chorus, WDG 0.2 kg / ha.

Beginning of flowering: Skor, KE (0.2 l / ha) or stroby, WDg (0.2 kg/ha).

End of flowering (fall of 75% petals): stroby, WDG, 0.2 kg / ha, or stroby, WDG + delan, WG, 0.2 + 0.4 kg / ha or Skor, KE, 0.2 l / ha. In 2007, the processing was not performed.

Hazelnut, Delan WG, 0.6 kg / ha (Stroby in 2007, WDG, 0.2 kg/ha).

Walnut, - Stroby, WDG + polyram, WG, WDG 0.2-1.5 kg/ ha (2006), delan WG 0.6 kg-ha (2007), Stroby, WDG, + delan WG 0.2-0.4 kg (2008-2009))-hafundazol, SP, 1.0 kg / ha, or strobes, EDC, 0.2 kg / ha.

The growth and ripening: fundazol, SP, 1.0 kg / ha; or delan, WG, 0.6 kg / ha; or Skor, KE, 0.2 l / ha; or Stroby, WDG, 0.2 kg / ha; or polyram DF, WDG, 2.0 kg / ha.

Research methods – generally accepted [6].

The results

The impact of weather factors is noted in the spring and early summer months, in the most favorable conditions for disease development (rainfall and the establishment of an optimal average daily air temperature) when there is a development of primary and secondary infections of the scab.

In recent years, the aggressiveness of this pathogen increases dramatically: ascospores mature within a few days, conidial stage comes before the end of apple blossom. First scab spots appear on the leaves in May.

During the years of protection system testing for apple trees weather conditions in 2006, 2008, 2009, 2011, 2012 were most favorable for the development of scab. Leaves and fruits of susceptible varieties suffered infestation in the control variant of about 27.6 and 31.5%, of relatively stable varieties - 11.8 and 8.2, and in 2007, 2010. - 3.0 and 8.4; 1.6 and 2.5%, respectively.

One of the indicators of the disease development rate is the incubation period and the number of generations of the pathogen during the season. During scab epiphytoties (2006, 2008, 2009, 2011-2013.) the number of generations varied from 6 to 10, the length of the incubation period ranged from 6 to 14 days. With moderate (2007, 2010) development of the disease the number of generations was between 4 and 8, and the length of the incubation period - 8-16 days.

The results showed that varieties susceptible to scab can be effectively helped with the introduction of the prototype system. Its biological efficiency (BE) during the mass development of the disease on the leaves and fruit was 94.3 and 96.6%, standard - 94%, and economic - 68.6 and 82.1, standard - 80%; in the years of weak development - 95.0; 98.0; 96 and 93.5; 91.0; 90.0%, respectively.

For relatively resistant to scab varieties, indicators of biological effectiveness and uniformity of fruit in the experimental system of protection during the mass development of the disease was 94.9; 98.9; 96% and economic - 85.1; 85.3; 85.0%, respectively. During the weak development of the disease the BE was high in both systems. BE of leaves and fruit for the prototype system was 97.0 and 98.0% (standard of fruit 97.0%), economic - 94.0 and 96.5% (95%), respectively.

Monitoring of functional state of plants in apple plantations of horticultural farms in Tambov and Lipetsk regions regarding the photosynthetic activity of the leaves (Fv / Fm) revealed that the prototype system is beneficial to all physiological processes. Thus, even in the extreme conditions of the growing season in 2010 the average values of this indicator for Zhigulevskoye, Lobo and Martovskoye totaled 0.58 ... 0.61 rel. u, Vishnevoye - 0.62 (average), while the optimum is 0.75, whereas business system data rates were 10 ... 15% lower, and they did not exceed 0.45 rel. u. for the control varieties.

It should be noted that the restoration of the functional activity of plants in experimental variants proceeded faster. If average vegetation values of photosynthetic activity of leaves of the control plants in 2011 were 15 ... 20% less than optimal; for tested variants, these values almost reached the optimum - 0.69 ... 0.73 rel. u, depending on the variety, options and plantations. An important thing was the fact that the variance within a single plant in the experimental embodiment was 0.0016 ... 0.0011 rel. u, indicating a sufficiently high level of stability of condition of the plants under control - 0.0049.

As a result of years of research, we found a positive impact of evidence-based system of plant protection on the dynamics of the photosynthetic processes during the growing season. It was found that the values Fv / Fm in the experiment is close to optimal, whereas photosynthetic activity decreased significantly in July for the control group (the impact of extremely high air temperatures amid drought) and abnormally increased in September and October, which increases the risk of winter damage to apple trees.

Thus, the application of scab protection systems for apple orchards, taking into account the stability of the variety and the physiological state of plants in a particular growing season, allows not only fighting pests effectively, but also stabilizes the operation of the exchange systems, which increases the resistance of apple plants to exogenous emotional stress.