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The Search for New Integrated Production Methods
Several innovative methods and approaches under evaluation at MSU and elsewhere may help
assure consistent and economical cherry production while reducing possible environmental risks.
Some example include:
- Bt and insect growth regulators.
Insect growth regulators, which interfere with the
development of insects, and Bt, a biological pesticide, control insects in the order
Lepidoptera. Most of the species in this order are moths and butterflies that exist as
caterpillars or worms when young. Green fruit worm, an early season Lepidoptera pest
of cherries, can be severe. Most pesticides applied to control other cherry pests, do not
control green fruit worm and good biological control has not been developed for this pest.
This results in the use of harsher pesticides that can cause secondary problems, which end
up increasing the population of European red mites and two spotted spider mites. The
potential of Bt and insect growth regulators for green fruit worm control and for avoiding
the secondary mite problems on tart cherries is being evaluated.
- Pheromone disruption.
The future value of pheromones, which disrupt normal mating
behavior of insects, in cherry IPM programs is still uncertain. Pheromones could work
well in controlling the borer complex (greater peach tree, lesser peach tree, and American
plum borers), which dramatically shorten the life of trees. Research continues to develop
a pheromone dispenser that will disrupt all three species simultaneously.
- Spray application technology.
Research at MSU in this area continues, with a goal of
improving efficiency and efficacy while reducing application rates even further. Equally
significant is the fact that spray manufacturers are also developing newer systems to
improve spray application efficiency.
- Disease resistance and plant breeding.
Development and planting of varieties with
high resistance or immunity to brown rot, leaf spot, and powdery mildew could result in
significant reductions in fungicide use on cherries in the future. Potential new varieties
are being evaluated for many characteristics including susceptibility to diseases in small
Varieties that perform well will be released to growers for further testing and eventual
planting in commercial blocks. For example, while the Hungarian variety Balaton offers
only minor improvements in disease resistance (compared to Montmorency), it possesses
excellent fruit quality and may offer unique marketing opportunities for the industry.
However, varieties that exhibit high susceptibility even to minor diseases are not released
for general production. For example, an excellent quality cherry variety from Hungary
was not released to Michigan growers recently because of its high susceptibility to
European brown rot. This cherry variety, if grown widely in Michigan, would have
increased fungicide use even on other varieties due to concerns that disease could spread
from infected plantings.
MSU (in cooperation with the cherry industry) has a large tart cherry breeding program
utilizing several potential sources of disease resistance. For instance, seedlings of a
cherry cultivar with field resistance to leaf spot in Hungary are also being evaluated in
Michigan as a source for leaf spot resistance. Rigorous nursery and field testing is
conducted to accurately establish the disease resistance characteristics of the seedling
population. although a few cherry seedlings have appeared resistant to leaf spot in
nursery plantings, upon retesting they were found to be susceptible. It will take many
years to find a genetically usable source of disease resistance and then to incorporate it
into acceptable varieties.