Stem rust has been detected in a crop of Yitpi wheat in the Mallee near Woomelang by a consultant.

The Department of Primary Industries is advising farmers and agronomists in all cropping regions of Victoria to monitor their wheat crops for stem rust, especially susceptible varieties like Yitpi. If stem rust is detected, then spraying a foliar fungicide is recommended to provide control of the disease.

What to look for

Stem rust is characterised by reddishbrown, oblong pustules. The pustules have a characteristic torn margin, and can occur on both sides of leaves, as well as on stems and glumes. At this time of the year it will be necessary to look closely at plants to detect the small pin head size pustules. (See Figures 1-3).

Monitoring

Farmers and agronomists are advised to actively monitor for symptoms of stem rust and inspect crops every 4 to 7 days if it has been detected in your region, or every 7 to 10 days if not. Stem rust can affect all parts of the plant and will most likely appear on the  leaves when plants are in the tillering stages so careful inspection of leaves as well as the lower stems is important.

When to spray?

Fungicides will give better control of stem rust when applied early in the epidemic. The degree and duration of suppression depends on the  application rate and coverage. Under high disease levels, high rates should be used as poor control is likely when low rates are used

Fungicides

There are a number of products registered for the control of stem rust in Victoria. However, it is always important to read the chemical label before use. Note that tebuconazole (eg. Folicur®) degrades slowly in plants. Therefore, restrictions apply regarding the total amount  that can be applied per season to one crop. Only one application of any product containing 430 g/L tebuconazole at the maximum label rate of 290 mL/ha can be used in a crop. Consult your local agronomist for more information regarding a fungicide control of stem rust.