PROJECT DESCRIPTION AND RESULTS
I planted 500 sand hill plum (Prunus angustifolia) seedlings on three eroded terrace contours, spaced 40 feet apart in March 1995. These plum seedlings are unselected seedlings offered by Kansas State and Extension Forestry for conservation plantings. These native woody shrubs grew rapidly and served as a windbreak for soybeans which we planted between them, reducing wind erosion. Overtime, the plum hedgerows will also trap eroding soil from the cultivated crops, creating natural terraces that reduce water erosion.
Effects of plum hedgerows on soybean yields: Just before soybean harvest in October 1996, I hand-harvested and weighed soybean yields from eight sample areas to determine if competition from the plum bushes would cause any reduction in soybean yields. Samples were taken from four paired replications, six feet away and 20 feet away form the plum hedgerows at each replication. Two 10-foot-long rows of plants were harvested within each sample are, and the beans were shelled from the pods and weighed.
Yields did not differ significantly based on distance from the plum plantings. The four plots six feet away from the plum hedgerows yielded an average of 187 g per plot, while the four plots 20 feet away from the plum hedgerows yielded an average of 171 g per plot. Thus the land between the plum hedgerows can be fully utilized for field crop production without any yield loss due to competition from the plums.
Costs and profits: Costs of planting and maintaining the plum hedgerows were recorded. The profit value of the soybeans which could have been grown on the terraces wre calculated and compared to actual profits from plum seed and fruit sales, which began in 1997.
Costs of planting and maintaining the plum hedgerows:
• $250 cost for 500 plum seedlings
• $700 labor (@ $10 per hour) for 70 hours to plant plum hedgerows and control weeds for first 3 years
• $292 herbicide costs (Roundup) for first 3 years ($96 per season)
• $1242 total costs of plum hedgerows for first 3 years
Profit value of the soybeans grown between the plum hedgerows:
• $74 per acre in 1996
• $54 per acre in 1997
Total area taken away form soybean production by the plum hedgerows: 12’ wide x 656’ long x 3 hedgerows = 23,616 square feet = 0.54 acres
If soybeans had been grown on these terraces, profit would have been: $40 in 1996 and $29 in 1997.
Sales of plums in 1997: 200 lbs. fruit sold fro $0.60 per pound = $120
Labor to harvest plums: 5 hours @ $6 per hour = $30
Net return = $90 per half acre, or $180 per acre
This represents only about 10% of the potential crop.
Potential gross return of sand hill plum hedgerow: $2400 per acre per year
Costs per acre each year:
– harvest labor @ $6 per hour (100 hours) = $600
– herbicide costs each season = $190
– weed control labor each season @ $10 per hour = $90
Total costs each year: $880 per acre
Net profit per year $1520 per acre
This would pay off the initial investment, including the lost profit from soybean production in the area taken up by the plum hedgerows, within 5 years of planting the hedgerows. There after the plum hedgerows would produce a profit of about $1500 per acre, which is 23 times greater than the profit form soybean production.
Evaluations of bacterial spot resistance in sand hill plums: I evaluated individual plum bushes for resistance to foliar bacteria spot, a common disease that can reduce yields, in midsummer 1996 and midsummer 1997. I used the leaf infection severity scale developed by Werner et al. (1986):
0 = no lesions observed on the foliage
1 = trace a few leaves with lesions observed
2 = up to 5% of the foliage with lesions
3 = 6% to 15% of the foliage with lesions
4 = 16% to 40% of the foliage with lesions
5 = >40% of the foliage with lesions
Table 1 presents the number and percent of plum bushes observed at each rating level during the two years. Bacterial spot was much more severe during 1997 than during 1996, due to wetter weather in 1997. No bushes were observed that completely escaped the disease (rating 0), but in 1996 almost 25% of the bushes had only trace infection (rating 1). In 1997 only three bushes, less than 1% of the 479 bushes rated received a rating of 1.
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This data illustrate the large plant populations needed to select for disease resistance, and the problems that can arise from too much or too little disease pressure. Many of the apparently-resistant plants from 1996 proved more susceptible in 1997 with greater disease pressure, but limiting the selections to just the three most disease-resistant plants of 1997 would narrow the genetic base unnecessarily. Combining both years’ data yields the most useful analysis. Besides the three plants rated “1” in both years, 38 plants rated “1” in 1996 and “2” in 1997, which is still quite healthy with 5% or less of the leaves showing bacterial spot lesions.
Sand hill plum fruit quality evaluations: After the plums started to bear in 1997, I evaluated them for bloom date, yields per bush and per length of hedgerow, fruit size and color, percent pulp, percent soluble solids, and resistance to brown rot of the fruit. I selected three superior seedlings in 1997 and plan to select others in 1998, when more bushes are bearing. One of these three selections was also resistant to bacterial spot, rated “1” in 1996 and “2” in 1997. A second selection was rated “2” in both years, while the third was unfortunately rated “1” in 1996 but “4” in 1997. Superior selections will be propagated by cuttings and used in a breeding program to combine superior fruit quality, high yields and disease resistance.
My cooperators and I are developing a Kansas Extension publication detailing the costs and benefits of creating naturally-forming terraces with woody plant hedgerows, particularly those of sand hill plum. I took slide photographs of the plum hedgerows and soybeans being harvested, of bacterial spot and brown rot, and of fruit selected as superior. I presented a slide talk at a trade show in Wichita in March 1998, and will present another talk at a sustainable agriculture meeting. An article will also be published in a farm magazine.
Sand hill plum germplasm collection: Superior wild sand hill plums were collected on a trip to central Kansas in July 1997, and the seeds of these have been stratified and will be planted in spring 1998. These seedlings will be further evaluated, and superior selections will be used in the ongoing breeding program. Superior selections of sand hill plum will be propagated by cuttings and made available to interested farmers.
Werner, D.J., D.F. Ritchie, D.W. Cain and E. I. Zehr. 1986. Susceptibility of Peaches and Nectarines, Plant Introductions, and Other Prunus Species to Bacterial Spot. HortScience 21:127-130.