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- Small Fruit Research Projects
Underway at Penn State
- By Kathy Demchak
Penn State University
- Several small fruit research projects are underway at Penn State. These experiments should give growers some information on growing systems and options they may wish to implement on their own farms.
Herbicides for establishment
In response to the need for weed control options during the planting year, experiments were established at the Penn State University (PSU) Horticulture Research Farm at Rock Springs, Pa. in 1999 and at sites on seven grower farms located across Pennsylvania in 2000. Treatments applied at the time of planting included Devrinol 50WP at 4 lb/a, Dacthal 75WP at 12 lb/a, Dual Magnum at two rates and Prowl. These last two herbicides were not used according to labeled use patterns, and were included only to provide data to support possible emergency exemption or special local needs labels if pursued.
However, some general observations:
1) all herbicides tested had some negative effects when compared to the hand weeded control. However, no herbicide tested had as many negative effects on the plants as uncontrolled weeds.
2) Plants coming from less vigorous crowns are more likely to be injured by herbicides than those from stockier crowns.
3) The best herbicides for any particular site will depend on weed species present.
Even though herbicides have their place in many weed control programs, the importance of reduction of the weed seed bank prior to planting and cultivation cannot be forgotten. One very apparent shortfall of selective herbicides is that each one controls only certain weeds, which allows other weed species to take over. If there is a large weed seed bank of many species, growers will not get weed control regardless of which herbicide they use. Instead, they just change the species of weeds present in their planting.
4) It is especially critical to keep weeds under control as plants begin to runner and while they fill in the beds.
Strawberry plasticulture
Many Pennsylvania growers are interested in or have been experimenting with strawberry plasticulture. However, very little formal research has been conducted on this system here. It is uncertain whether strawberry plasticulture is profitable given our short growing season. Finding the combination of cultivar and planting date will help determine recommendations for growers with similar environmental conditions.
An experiment, established in 2000 at Rock Springs, evaluates Chandler, Camarosa, and Sweet Charlie plug plants, and Avalon, Allstar, and Latestar mother plants planted in mid-August, late August, and mid-September. The earliest planting date was the best for the plug plants, while it appeared that by using mother plants you could buy some time in the fall if planting were delayed, as planting date appeared to make less of a difference with mother plants.
High tunnel production
Previous field research on fall-bearing raspberries cultivars at Rock Springs showed that up to 85% of potential yield could go unharvested due to early frosts. Therefore, the fall-bearing raspberry cultivars Heritage and Autumn Britten were grown in tunnels with extension of the fall picking season as the primary objective. Yield obtained per linear foot of row during the planting year was nearly as high as that which could be expected from a mature three-year-old field planting.
Plants were planted about one month earlier than they could have been unprotected, and fall harvest was extended by three weeks. An extremely high percentage (98%) of fruit harvested was marketable and shelf life was more than doubled even though no fungicides were used, compared to fruit from a field planting under a standard fungicide spray program. The biggest production problem encountered was two-spotted spider mites, but early release of predatory mites kept them under control. These plantings are being held over for harvest in 2001. A new experiment was established in the high tunnels during the spring of 2001 which will evaluate, from the cooperative breeding program with the states of New Jersey, Maryland, Virginia, Wisconsin, the fall-bearing raspberry cultivar Josephine, a fall-bearing raspberry numbered selection ND-f1 and a Wyeberry numbered selection QDE-1. Heritage is grown as a standard.
The strawberry cultivars Chandler, Camarosa, and Sweet Charlie were planted in mid-August and mid-September of 2000 for a comparison of planting dates and for comparison to the field planting discussed above. Harvest began three weeks earlier than in the field. Overall, Chandler was the most consistent performer, planting date made little difference in yield.
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