Continued vigilance critical to cherry trees

The 2011 cherry season is here. Tree maintenance and compliance with Montana and county laws regarding pest control is very important.

Our Pest Management Area (PMA) consists of all lands within two miles of Flathead Lake in Flathead and Lake Counties.

The primary pest we deal with is the Western Cherry Fruit fly(Ragoletis Indifferens).

However, we now have to monitor for another pest (Spotted Wing Drosophilla), which is much harder to find because of its size(It has to be identified under microscope).

The Spotted Wing Drosophilla came from Asia on imports. It has started to cause serious problems for fruit growers on the West Coast in Washington, Oregon and California.

The new fly is becoming widespread because it is attracted to all kinds of fruit, not just cherries.

Therefore, control of pests on cherry and other fruit trees is critical. Organic sprays currently used for the cherry fruit fly are not effective for this new fly.

It will be very difficult for organic growers to control when this new fly takes hold.

Our goal as pest managers is to help growers harvest a healthy, pest-free crop so they can maintain their markets around the world.

Montana law states that any grower, commercial or otherwise, must control the pests in his or her orchard trees.

No matter if you only have one tree or a thousand trees, you must control the cherry fruit fly.

When the cherry fruit fly is not controlled, there can be industry-wide ramifications. We take a zero-tolerance approach to the cherry fruit fly.

There is a risk of losing important markets that will shut down Montana cherry growers if a cherry fruit fly is found in our fruit.

The success of the Flathead cherry industry depends on every grower, large and small, controlling the cherry fruit fly.

Just one larvae (worm) can stop exports, shut down packing plants and stop pickers from picking.

Thus, it would be a huge loss of income for this industry.

Monitoring cherry fruit flies is an essential part of my job, as well as for every Montana cherry grower. Traps are used for monitoring seasonal emergence and non-compliant areas.

You might see the yellow sticky card traps along the roadside or in an orchard. They are used as an indicator of the cherry fruit fly presence, not as a control agent. More than two cherry fruit flies per trap indicates a real problem.

The life cycle of the western cherry fruit fly is continuous from mid-June to mid-September. They overwinter (in the ground) as pupae. Adult flies begin emerging from the soil in mid-June and continue throughout the summer.

Females reach sexual maturity in seven to 10 days. After mating, the females lay one egg per cherry, by boring into the fruit. They can lay up to 350 eggs. The eggs hatch in five to nine days.

The larvae tunnel through the fruit feeding for one to three weeks, then drop to the ground to pupate.

This continues into September. Since fruit flies reproduce continuously all season long, control methods must be used during this entire period.

One or two control applications per season are simply not enough.

Means of control and rate of application are very important. As a cherry tree grower, you should begin your control program by mid-June.

This control program should continue on a regular basis every six to 10 days, depending on the weather and on what you are applying.

For purchase of insecticides, spray rates and information, contact your local extension agent or licensed pesticide dealer.

By managing your cherry trees, you will be helping all Flathead cherry growers.

Please don’t hesitate to contact us, Chris Beason (214-5425) or Tom Lawrence (250-8213), with questions regarding cherry pest management.

Thank you for doing your part in keeping Montana’s cherry industry healthy.

Beason deals with cherry pest management in Flathead and Lake counties.