Tree fruit production is a small part of the horticulture farm, but its stand of apple and peach trees is large enough for plant scientist David Eissenstat to get at the root of how fruit trees absorb nutrients. Each year, trees produce fine, hair-like roots to take up water and nutrients from the soil. There is a specific window of time when these roots can absorb fertilizer or pesticides.

Postdoctoral researcher Astrid Volder, left, uses “root boxes” with clear acetate sides to observe how apple trees form the fine roots used to take up nutrients. At right, plant physiologist David Eissenstat inserts a cylindrical video camera into clear tubes embedded into the root system of a Rock Springs apple orchard. The camera records root growth from formation to death.

Toward the end of the growing season, or when the tree is under stress, a tree will shed its fine roots. Eissenstat and postdoctoral researcher Astrid Volder are using several methods to trace apple and peach tree root growth to give growers more accurate information for nutrient applications.

One method uses a $20,000 custom-made cylindrical video camera. The researchers slide the camera into clear plastic tubes embedded four feet into the fruit trees’ root zone. While taping, they measure root growth using scribed windows on the exterior of the tubes. Each videotape is entered into a database that follows every root’s life history through the growing season, from formation to root death. Eissenstat outfitted more than 64 trees at Rock Springs with root tubes, and more than 200 others at sites around the state.

Another method uses “root boxes” with clear acetate sides to observe root activity. Volder dug out soil at the base of 30 apple trees to install the boxes. Through an observation window divided into three sections, Volder injects high nutrients, no nutrients, and low nutrients, respectively. As she measures the uptake of nutrients into the roots, she documents at what age and stage of root growth the roots are most efficient. Coupled with the video data on root growth, researchers can use root box observations to establish the optimal application timeline for fertilizer and pesticide applications. “Timing is everything in fruit management,” Eissenstat says.

Plant pathology farm manager Larry Jordan, foreground, plans out the day’s work with assistant farm manager Randy Dreibelbis. On the plant pathology farm, Jordan creates conditions that let scientists study plant diseases. He also manages the USDA Pasture Research farm.

Larry Jordan, plant pathology farm manager, has an unusual responsibility for a farmer: he creates conditions under which crops can be infected with any one of a number of diseases. The goal of the Department of Plant Pathology is to select and breed crops that can stand up to bacterial, fungal, and viral diseases, and research conducted at the department’s farm leads to the development of crops with increased resistance to serious pathogens.

The plant pathology farm is divided into two-acre research plots, and every inch is equipped with a high-tech irrigation system—the better to create the environments of excess moisture so loved by plant diseases. “An epidemic is great news for us,” Jordan says, laughing. “Our mission is to find better management practices for major plant diseases.”

Jordan and his staff oversee each phase of the farm’s research projects, from plowing the field to planting and making every chemical application. Most of the scientific work is done by graduate students and faculty researchers, although Jordan keeps careful records of chemical applications, planting dates, special treatments, and crop types, in case of lost or misplaced data. The farm crew also must react quickly to Pennsylvania’s changing conditions. “If needed, we can dig up one crop and plant another one when new problems affect our farmers,” he says.

One of the prime directives for the plant pathology farm is to create field research experiments to help various agricultural industries cope with major disease threats. Plant pathologist Jim Travis has created a vineyard at Rock Springs to help serve the grape-processing industry and Pennsylvania’s rapidly expanding wine industry. “We have 15 wine grape varieties planted, including Chardonnay, Merlot, and French hybrid grapes, and two processing varieties, Concord and Niagara,” Travis says.

Travis has also planted grapes at Penn State’s Lake Erie Regional Grape Research and Extension Center. He evaluates how grapes grow in both locations, as well as differences in disease development. Grapes for processing and winemaking are subject to several devastating diseases, including Botrytis (gray mold), downy mildew, and black rot. “We have brought in some pretty sophisticated weather equipment so we can closely monitor the relationship between climate and disease development,” he
explains. “As we gather information from both sites, we can create computer models that not only predict disease outbreaks, but also help producers reduce the application of fungicides.”

Plant pathologist Barbara Christ conducts potato-breeding and disease-resistance studies at the Rock Springs farm, focusing on diseases such as early and late blight. “Our mission is to develop potatoes that are adapted to Pennsylvania and have resistance to diseases,” she explains. “If varieties are more resistant, growers can use less fungicide. Also, some diseases have no good chemical control, so resistance is the only tool available.”

In conjunction with other breeders, Christ has co-released 11 new potato cultivars, which are now grown on more than 18,000 acres across the Northeast. Currently, she is working with wild potato species that have tremendous disease resistance, looking for ways to transfer that resistance into standard varieties while still retaining the standard varieties’ desirable characteristics.

Christ also conducts research on integrated pest management (IPM) strategies. “Growers need new varieties, but developing a new cultivar can take 10 years. They also need techniques they can use now. We can get results from IPM projects in a year or two, providing information that helps growers slow down diseases through cultural practices.”