Managing Mites in Ontario apple orchards using new products

In the last few years there have been several new products registered for managing mites in Ontario apple orchards. These registrations have provided apple growers with many excellent options for managing mites, and allow growers to follow resistance management strategies. There are several key things that growers should remember to help manage mites effectively.

1. Avoid using products that can cause mite outbreaks. Pyrethroids (Matador, Decis) have been shown to cause mite outbreaks in orchards. Research suggests that repeated applications of some of the new neonicotinoids may increase European red mite egg laying or may be harmful to beneficial mites. As a result carefully monitor mite populations whenever using any neonicotinoids in orchards.
2. Monitoring mites is an important component of any IPM program and scouts should be taking mite samples and analyzing them under the microscope on a weekly basis. Careful monitoring can allow growers to manage mites before their populations reach damaging levels.
3. Take note of beneficial mites and insects when monitoring; these may be very effective in keeping pest mites below threshold levels.
4. Be aware that miticides are often highly selective. A given product may not be effective on all types of mites (European red mite, two spotted spider mite and apple rust mite), all lifestages (eggs, nymphs, adults), or even both sexes. To optimize spray timing and to assist in choosing an appropriate miticide, it is critical to identify the species and dominant lifestages present. The label rates of some miticides may differ depending on the species - be sure to refer to the label.
5. Some of the newly registered miticides should be applied at a lower threshold than other products to optimize their efficacy.
6. Miticides are most effective when applied alone, using recommended rates and high water volumes (>1000 L of water/ha). Reducing the amount of water applied or decreasing the rate may result in substandard results. Good coverage is essential.
7. Apply each miticide only once per season to delay the development of resistance. If miticides need to be applied two years in a row, be sure to use products from different chemical families to avoid the development of pesticide resistance. To help with this, make sure to check out the "group" number on the label.
8. Some of the newer miticides are slower acting. This must be taken into consideration when applying the product (follow thresholds). For products with slow knockdown, wait 1 to 2 weeks after spraying to determine if the product was effective.

Table 4. Activity of Miticides Registered on Apple and / or Pear in Ontario*

* Registered for use on apple or pear unless indicated otherwise. Use established thresholds to time applications. Miticides are most effective when applied alone, using recommended rates and water volumes. Apply each miticide only once per season to delay the development of resistance.