2008 Cercospora Spray Program Recommendations

Dr. Ron Pitblado, Weather INnovations Incorporated
Janice LeBoeuf, OMAFRA Vegetable Crop Specialist

Update: Tilt has received an emergency use registration for Cercospora leafspot in sugarbeets for 2008. See the recommended the spray program below.

The BEETcast program ensures that you get the most out of the dollars you spend on disease control by suggesting the most effective timing of fungicide applications for Cercospora leaf spot. You can tailor-make your spray program based on the level of risk management you are comfortable with. Remember, your spray decisions and the resultant sugar harvested, will affect you as a co-op shareholder in the Michigan Sugar Company.

* New this year is the introduction of Roundup Ready sugarbeet varieties. There has not been sufficient time for plant breeders to incorporate higher levels of Cercospora resistance into these varieties and so the current RR varieties are considered less resistant than the standard company-approved varieties. Growers are asking whether this fact should alter their fungicide spray program. In the development of BEETcast the susceptible sugarbeet variety E17 was used to determine the spray timing intervals. Research by the Michigan Sugar Company has indicated that the variety Crystal RR827 is slightly more susceptible, and Hilleshog's RR varieties HM27, HM28 and HM29 are no more susceptible to Cercospora than E17 from which BEETcast was developed. With that in mind, we believe the current spray timings are still valid. It is very important to use BEETcast to make sure that your first and most effective spray application is properly timed, especially for these new RR sugarbeet varieties.

1. Rotate fungicide groups. Never, ever use Headline back to back or Senator back to back.
2. Select varieties with resistance to Cercospora leaf spot, if possible.
3. Be on time with your first application of the season. It is often the most valuable spray. Currently your choice of spray materials is limited compared with your co-op colleagues in the US. Recognizing what is registered in Canada, it is recommended that you start your fungicide spray program with Headline. Follow BEETcast to time this application correctly.
4. Use BEETcast to ensure that subsequent fungicide applications are also timely. If the program was started with Headline, Tilt is a good choice for your second application. Senator is suggested if a third application is required. If necessary, you can then come back with Headline or Tilt. Note that in Michigan, Topsin (Senator in Canada) is never used alone, always tank-mixed with a fungicide in the mancozeb group. As stand-alone products, however, mancozeb/metiram fungicides should be used with a shorter respray (DSV) interval.
5. Use at least 30 gpa of water for fungicide application.
6. Scout your fields often during Cercospora season to monitor disease development and fungicide effectiveness.

Headline, Senator, and Tilt are in different chemical families, so there is no reason to use any of them back to back. Please rotate between them to help maintain their effectiveness. As new products are registered, we will still need the existing products for resistance management. OMAFRA and Michigan Sugar Company will keep growers updated on new registrations.