Phytophthora: mix and alternate for results

In 2023, Syngenta has set up 33 trials for the control of late blight in the BeNeLux, which is undoubtedly a record for the industry. These tests took place under different conditions, including the presence/absence of resistances, disease pressure, varieties, and climate.

One of the main objectives of the 2023 trials was to compare the effectiveness of single active ingredients with combinations, i.e. mixing products with different mechanisms of action.

Mengen
The results show that in all cases combining (mixing) active ingredients is better than using single active ingredients. Adding a partner to mandipropamid significantly increases the effectiveness of the treatments, regardless of the situation (with or without resistance). The combinations of mandipropamid with fluazinam (the Vamos Pergovi pack) or propamocarb (the Pergovi pro pack) showed excellent effectiveness.

Alternate
Combining products with different mechanisms of action has, as discussed previously, shown significantly improved effectiveness. However, this result can be further improved by alternating these combinations and no longer spraying in blocks. This is illustrated in the graph at the bottom of this page, with the alternation strategy. In addition to even better control of phytophthora and therefore more effective resistance management, rotation has another major advantage. Most products against phytophthora may be used in an interval of seven days. Under high pressure and favorable conditions, this interval is too long, especially with the aggressive strains currently present. By alternating, it is possible to spray at shorter intervals, which can further increase effectiveness.

In Summary
The total of all tests carried out by Syngenta in 2023 to combat phytophthora can be summarized as follows:

• Mixing products (active substances with a different mechanism of action) is better than using products solo.
• Alternating spraying instead of in blocks leads to a better result and makes the spraying interval flexible, so that you can respond to the circumstances.
• Applying both mixing and alternating results in the best possible control of phytophthora, and prevents the selection of strains and the development of resistances on the one hand, and disappointing effectiveness against the new, very aggressive strains on the other.