Controlling the pathogens responsible for the two most important diseases of apple orchards, apple scab and powdery mildew, requires regular crop protection measures throughout almost the entire growing season. Fortunately, a wide range of highly effective products is available against both pathogens, including both systemic and contact active substances. The active substances in Vegesol eReS fungicide are effective against both of these pathogens when applied at the appropriate time during the growing season.

Control of apple scab should begin with the onset of ascospore release, often as early as the mouse-ear stage. Cool spring weather and prolonged leaf wetness limit the range of active substances that can be used successfully. Copper remains a highly reliable option under these conditions, as even very small quantities of this active substance can destroy germinating ascospores, and resistance to copper does not develop. The challenge when using copper is that, as a contact active substance, it must be present on the plant surface precisely when and where the fungus germinates.

In the GEP trial conducted in 2017, three different application rates of Vegesol eReS were applied three times before flowering and protected the plants against apple scab to varying degrees, with the highest application rate providing the best efficacy. By flowering, scab symptoms had already appeared on more than half of the leaves of the untreated apple trees. The standard combination (copper hydroxide 50 WP (2 kg/ha) + elemental sulfur (3 kg/ha)) also produced good results. The major difference was the amount of copper active substance applied: thanks to BVN’s patented film-forming technology, only 76% of the amount of copper used in the competing standard treatment was required to achieve the same biological efficacy (Figure 1).

As the first element of a long-lasting apple scab control strategy, we recommend applying Vegesol eReS at its maximum authorized rate in pre-flowering treatments. This effective preventive treatment provides a strong foundation for the systemic products to be used during the period of intensive growth after flowering. Once ascospore release has ceased and the period of conidial infection begins, contact products alone are sufficient during the summer. Vegesol eReS, with its two active substances, is also an excellent choice at this stage.

Control of powdery mildew begins with pruning every year, as terminal buds are frequently infected. Primary infection originating from these buds can be difficult to stop, and conidia begin to disperse as early as the green bud stage. The objective is to stop conidia formation at primary infection sources and prevent secondary infection. Systemic active substances should also be used, particularly during the bud stage and after flowering, but sulfur also provides excellent efficacy and forms an integral part of the control programme. If only sulfur is available, shorter spray intervals are required and the residual activity of the product becomes a particularly important factor. The same principle mentioned above also applies to sulfur: as a contact fungicidal active substance, it must be present where and when the fungus attacks. This can only be achieved if the applied dose is not washed from the plant surface by the first rainfall or morning dew.

In such situations, Vegesol eReS stands out from competing sulfur-containing fungicides. Its liquid formulation makes dosing and application easier, while most importantly, its plant oil content and patented film-forming technology provide the required long-lasting activity. The oil polymerizes in an oxidative environment, preventing the sulfur from being rapidly washed off.

In a demonstration trial, three treatments were applied before flowering to the powdery mildew-susceptible Jonathan apple variety. Increasing application rates of Vegesol eReS resulted in progressively better efficacy. The authorized application rate produced better results than another sulfur-containing product. Vegesol eReS achieved this despite the amount of sulfur applied being only 60% of that used with the competing product. In the untreated control plots, the incidence of shoot infection was close to 100% (Figure 2).

Reducing environmental impact is one of the most important objectives in modern agriculture. With this in mind, we confidently recommend BVN’s oil-based products to growers, particularly for use during the growing season. Our copper-containing products make it easier for growers to comply with the 4 kg/ha limit for copper application without having to compromise on the high level of efficacy they are accustomed to.

All package sizes of Vegesol eReS are available without restriction and are also approved for use in organic production.