Reduced Chemical Input Production of Peaches

Reduced Chemical Input Production of Peaches

Summary

Rationale:
Synthetic chemical inputs for peach production in Michigan and the North Central region of the
U.S. have risen steadily since the turn of the century. It has been increasingly difficult for
growers to control certain insects and disease problems through conventional means, and the
marketplace is calling for a greater number of fresh products to be grown in a reduced chemical
environment.

Objectives:
1) To integrate technological advances in the following areas: fertilizer and nutrition, ground
cover management, insect and disease control, and horticultural practices into orchard systems
and compare them with conventional systems.
2) To demonstrate to growers the effectiveness of these systems.
3) To reduce pesticide and fertilizer inputs into the system while producing a high quality crop.
4) To monitor ground water and fruit for residues to determine the effect of these systems on
contamination.

Methods:
This project brought together science and education from Horticulture, Entomology, Pesticide
Research, Weed Science, and the Cooperative Extension Service with grower organizational
involvement for the express goal of reducing crop chemical dependency (pesticides, herbicides,
and fertilizer) for peaches. It also compared the chemical residues of the more important
compounds in the ground water and the fruit for conventional, moderate input, and low input
systems under Michigan commercial conditions at the new Southwest Michigan Research and
Extension Center (SWMREC). This was accomplished in three phases: 1) establishment of
different orchard systems at SWMREC, 2) development of educational programs for growers
concerning the effectiveness and incorporation of these techniques in grower operations, and 3)
monitoring pesticide and fertilizer residues in the fruit and in the ground water.

Results:
Total synthetic chemical applications for the moderate and low-input were reduced from 18 to 9
and 3, respectively, when compared with the control. Weeds were controlled in the low-input
treatment with straw mulch, and chemical fertilizer was reduced by half in the moderate input,
and to zero by using horse manure in the low-input. Yields in 1993 ranged from 346 bu/acre for
the conventional to 134 bu/acre for the moderate, and 163 bu/acre for the low-input. Fruit quality
in terms of fruit color and size was greatest for the moderate level, followed by the low-input,
and the conventional was least, while the conventional had the highest percentage of blemish free
at 97.5 percent, followed by the moderate level , 90.75 percent with the low-input at a very
respectful 82.25 percent, thus indicating that a very high percentage of the fruit could be grown
disease and insect free with a reduction in synthetic chemical applications from 18 to 2.
Endophytic rye was effective in reducing Tarnish Plant Bug and leafhopper populations in the
low-input, and oriental fruit moth disruption was also effective in these plots. It was noted that
peach scab became a problem in the low-input plots. Through the third growing year, there were
no significant differences in winter hardiness, tree growth, leaf nitrogen, ground water nitrate
contamination, or triazine residue due to the different treatments. The 1992 and 1993 crop
residues indicate that all residue levels are far below EPA's accepted tolerance, and that only
iprodione was higher in the conventional than the other plots. In most cases residues were below
normal detectable limits. Three major grower meetings have focused on this project and it has
been the subject of several lay articles.

Potential Contributions and Practical Applications:
We have demonstrated that peaches can be grown in a reduced chemical manner (less than 1/4 of
the conventional) with acceptable fruit quality and yield. This management strategy did not result
in a lower amount of chemical residue in the fruit, but did reduce nitrate in the water below the
trees. Several of the individual techniques employed in this study could be adopted by growers:
N application through the drip at .5 the ground rate, endophytic rye for the control of TPB and
leafhoppers, OFM control by mating disruption and perimeter spraying, brown rot control by
sulfur and sanitation, and control of weeds by straw mulch.

Farmer Adoption and Direct Impact:
Alternative production systems are a long-term endeavor, therefore adoption is slow. However,
growers are beginning to use the practices outlined above, as well as using: high density planting
systems, summer pruning, ground cover management, mowing to control leafhoppers, chemical
sprays based on monitoring where possible, N rate based on leaf analysis, perimeter spraying,
and OFM mating disruption.

Areas Needing Further Study:
Three areas needing further study include:
1) Economic analysis, and development of a decision support model.
2) On-farm demonstrations with growers in different areas of the state.
3) Development of systems for other major fruit crops.