The Fruit Growers News - February 2001

Growers and researchers have been generally pleased with the use of Apogee as a plant growth regulator and as a weapon to suppress fire blight.

A panel on “Experiences with Apogee in 2000” took place during the Michigan State Horticultural Society show in Grand Rapids in December. “We got it just in time to get some trials on. I’m very pleased with this product,” said Phil Schwallier, Michigan State University (MSU) Extension agent, one of the panelists.

Last April the EPA granted federal registration for Apogee on apples. The product, a plant growth regulator from the BASF Corporation, was designed as a production management tool for apple orchards to reduce vegetative growth, allowing a balance between canopy development and fruit production. The product has been registered in all fruit growing states except New York where registration is expected in the near future.

With a single application of Apogee there was a 50% reduction in shoot growth with the effect of Apogee taking two weeks to be able to observe, according to Schwallier.

“We would like to see Apogee put on at late bloom. Timing can be quite critical,” Schwallier said. He said adding ammonium sulfate 1:1 would increase its effectiveness. Ammonium sulfate helps with the absorption of Apogee and buffers the spray solution, according to Schwallier.

He advised growers not to put Apogee on dwarf trees too early as these trees present a dilemma to growers.

“On younger trees we want trees to grow and fill in space. We don’t want to reduce vegetative growth. But we also want young trees to receive resistance to fire blight,” Schwallier said.
Tom Rasch, an apple grower from Belding, Mich. said he plotted charts every seven days on trials with Apogee. Use of Apogee is recommended on high-vigor trees, on varieties susceptible to fire blight and in orchard areas where there is tree crowding and a dense canopy.

In untreated vs. treated trees the shoots in the trials were 16 inches (400 mm) compared to nine inches (250 mm) for a 40% reduction. There were 40 different total trials with Apogee. There was stockier wood on treated tree and more useable lateral shoots, possibly attributed to greater sunlight throughout the year.

Rasch told growers there is a possibility of smaller fruit and heavier set with Apogee use. “Red Delicious don’t like a full rate of Apogee,” Rasch told growers. However, there was a noticeable improvement of red color on the Red Delicious. On McIntosh trees there was no substantial difference in color. However the Apogee treated were not summer pruned and the control trees were.

“I think we’ve got a real good product. I’m sure everybody’s got a place on their farm to use it,” said Rasch. He told growers Apogee use reduces summer pruning 30% possibly up to 50% and 20-30% reduction in winter pruning.

Rasch said use of Apogee with improved sunlight results in stronger buds and overall higher quality fruit grown throughout the tree. Although there are lots of unknowns, the “buds are definitely stronger” with Apogee, Rasch said.

“There’s overall higher quality fruit in places where warranted,” he said.

Schwallier said that there is no known effect on fruit firmness but he believes it improves fruit set. He described Apogee as very important to the apple industry. “Get Apogee on early if you have trees that are vigorous,” he told growers.

He said the Northern Spy variety seems to be very sensitive to Apogee and more vigorous varieties need more applications of Apogee. Fuji only needs one application while Red Delicious and Empire treated with Apogee have had some problems.

Schwallier said the second application of Apogee should go on four to six weeks after the first application. He advised growers to apply their spray before it wears out. “In mid-June you’ve got to be out there. By the time the shoots start growing, you’re late, you’ve got to be there earlier,” he said.

The decision to make a second application of Apogee should be made in the fourth week after the first application. Schwallier said. Growers need to evaluate trees for vigor and also look at what kind of crop is on the tree. “If they have a light crop they should consider a second application,” he said. Some years a second application will not be needed on some blocks.

He told growers that with his experience with Apogee there was no carryover. “If it controls growth, it’s not extra vigorous the next year,” Schwallier said.

“I think it’s a fantastic material to help us deal with fire blight,” said Schwallier. Immediately past bloom is the period that is often the most critical for the shoot blight phase of fire blight, he said.

“The rate of Apogee per acre is more important than the concentration of the spray solution,” said Al Jones, MSU professor of botany and plant pathology.

At a meeting on fire blight in Southwest Michigan Jones showed a graph demonstrating that there was a reduction of fire blight with Apogee applied in bloom.

“The greater the amount of Apogee applied per acre the greater the response,” he said.

In their trials done at MSU in East Lansing there was a 50-90% reduction in fire blight. “It (Apogee) is labeled for the suppression of fire blight and I think that’s what it does. It does suppress the disease for about four to six weeks in early summer,” he said. Jones said Apogee was particularly effective on mature Jonathan trees and the best results were when Apogee was applied at a high rate when petal fall is showing on king bloom.

Jones cautions growers in Southwest Michigan that apple varieties like Gala and Honeycrisp that bring higher prices, are very susceptible to fire blight. “They’re taking a risk when they try to grow them,” he said. Jones said there’s been serious outbreaks of fire blight about every three years in Michigan and fire blight occurs in Michigan somewhere every year.

For product information on Apogee visit www.basf.com