Northern Michigan FruitNet 2009
NW Michigan Horticultural Research Station
District Fruit IPM/IFP Agent
Farm Mgr, NWMHRS
Agricultural & Regional Viticulture Agent
May 27, 2009
Following are two articles to help manage your apples this time of year.
APOGEE IN A NUTSHELL
Nikki Rothwell, District Horticulturist, MSU-E
Apogee is a plant growth regulator that helps regulate shoot elongation in apple trees.
Apogee helps control tree vigor, which can reduce the amount/intensity of pruning, decrease internal shading, and reduce canopy density for thorough pesticide coverage.
Apogee is a reliable tool for minimizing impacts of shoot blight caused by the fireblight pathogen. Shoots that have less growth are not as susceptible to fire blight.
Apply when vegetative shoot growth is less than three inches.
Optimal timing is king bloom petal fall.
Two more applications should be made at two-week intervals following the king bloom petal fall application.
Rate per acre is usually calculated on a tree row volume basis.
A two-thirds' rate is used season-long and is the starting rate for growers without experience using Apogee.
For example, if trees are at 75% tree row volume, then 24 ounces per acre is the seasonal rate (48 * 0.75 * 2/3).
Best results are achieved when the seasonal rate is split into three or four sprays: 8 + 8 + 8oz per acre for a total of 24oz per acre per season.
When fire blight is a severe risk, the first application at king bloom petal fall timing should be increased--the rate should be increased from 8oz per acre to 12oz per acre. If the first spray rate is increased, the second and third sprays should be reduced (12 + 6 + 6 = 24oz instead of 8+8+8=24oz).
Apogee tends to increase fruit set, hence more aggressive thinning is often needed.
If using Apogee, growers should increase thinning products by 10 or 15%.
Apogee is not compatible with calcium or boron in the tank.
Apogee should be applied after thinner applications. If the two-week timing interval is also the ideal time to thin, make the thinning application first and follow with Apogee a few days later.
Limits shoot blight strikes
Reduces # cankers
Controls shoot blight even if streptomycin-resistant strains present
THINKING ABOUT THINNING
Nikki Rothwell, District Horticulturist, MSU-E
Phil Schwallier, District Horticulturist, MSU-E, and
Factors to Consider:
Crop from last year. Light crop last year results in increased flowering in present year. Blocks where fruit was light will have increased bloom and an increased tendency to set fruit. We have observed tremendous bloom in apples around the region.
Frost damage. Some apple blocks were damaged on the evening of 3 May. If the frost took out the king bloom, thinning becomes more difficult.
Pollination and bee activity. Growers have reported improved hive quality this season over past years. Apple pollination weather has been excellent.
Weather conditions during thinning. Cold temperatures and sunny weather increase fruit set. Cloudy conditions increase thinning capabilities (See Table 1).
Tree vigor and growth. Trees that are growing vigorously with lots of leaves and lush growth present are harder to thin than less vigorous trees.
year’s apple crop for
we have a new tool from Drs. Terrence Robinson and Alan Lasko of
5/26/09 - This model output is based on the energy supply of apple trees at the NWMHRS beginning at petal fall. The premise behind this model is that when the fruitlets are in an energy deficient situation (demand is greater than supply), the fruitlets are sensitive (easier) to thin. When the tree has excess energy (supply is greater than demand), fruitlets are more resistant to thinning. The
NWMHRS model output suggest that tree demand is higher than the supply, hence, we had opportunities for good thinning earlier in May, but as we approach the end of May, those lines move closer together (supply is equal to demand), fruitlets will be more difficult to thin.
the model will predict normal conditions, normal energy levels, normal tree
sensitivity and normal thinning responses. However, thinning sensitivities can
be abnormal during the thinning window, and the model is intended to help
reduce mistakes of both over-thinning and under-thinning. If normal conditions
are predicted, then growers can use their judgment of thinning level desired
and adjust thinning aggressiveness to achieve ideal thinning. This model is
under testing for
WEBSITES OF INTEREST
Insect and disease predictive information is available at:
Information on cherries is available at the new cherry
Fruit CAT Alert Reports
This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm
Please send any comments or suggestions regarding this site
Bill Klein, email@example.com
Last Revised: 5-27-09