Applying Apogee to apples in 2015

Apple growers should protect valuable blocks with an increased seasonal rate.

Apogee has two major uses on apples, and they are to reduce vegetative growth and to suppress fire blight. This year, with very dangerous weather conditions during the bloom period, a high risk of fire blight exists. Applying Apogee at king bloom petal fall stage will provide fire blight suppression. Fire blight suppression has become a major use of Apogee in Michigan, but when Apogee is discontinued from an apple spray program where the trees have been sprayed every year, the trees will respond with additional excessive shoot growth.

Timing

Apply Apogee when the vegetative shoot growth is less than 3 inches. This is about a seven- to 10-day window commencing at the king bloom petal fall stage. Most years, all varieties can be treated at this time. The second application should be applied two weeks later and the third application two weeks after the second. Sometimes a fourth application is needed, but that is optional based on crop load and tree vigor.

An apple crop loss like this year will require a fourth and perhaps a fifth application of Apogee. Excessive rainfall and light crops will promote vegetative growth, therefore more applications and material will be needed.

Rate

Rate per acre is usually calculated on a tree row volume basis and can be adjusted to two-thirds of the label full rate. The two-thirds rate is the starting rate growers should consider if they don’t have any experience using Apogee in the past. Past experience on your block will indicate if this rate is too high or too low per acre. This suggested two-thirds rate per acre is a season-long rate per acre.

For example, if your trees are at 75 percent tree row volume, then 24 ounces per acre is the seasonal rate (48 x 0.75 x 2/3). Best results occur when seasonal rate is split into three or four sprays, for example, 8 + 8 + 8 ounces per acre. When fire blight is a severe risk, the first application at king bloom petal fall timing should be increased, perhaps as much as 150 percent of a split rate. For example, increase from 8 ounces per acre to 12 ounces per acre. Subsequent sprays, the second and third sprays, could be reduced, so the seasonal application would be 12 + 6 + 6 = 24 ounces per season. This year, 12 + 8 + 8 + 6 = 34 ounces will be needed to make up for the controlling effect of a normal crop and lesser Apogee rates.

In summary, Apogee is an excellent tool to help control vegetative growth and especially suppress fire blight spread among shoots and within shoots. For 2015, Michigan State University Extension advises growers to remember to protect valuable blocks with an increased seasonal rate.

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