Potato Growers Gather to Learn of Pennsylvania Trials

Crop consultant Bob Leiby, left, and and plant pathologist Mike Peck show off 18 varieties from the potato trials.

DANIELSVILLE, Pa. — More than 20 growers attended Tuesday’s twilight potato field meeting at Country View Farm in Danielsville.

The meeting, organized by Pennsylvania Co-Operative Potato Growers Inc. and the Lehigh Valley Potato Growers Association in cooperation with Penn State Extension, showcased 18 varieties of potatoes.

Sherwood Geiger, who has been farming on this property since 1967, and his son Joel grow 28 acres of Norwis potatoes and have an egg and potato route for restaurants four days a week.

For these trials, four hills were set up for each of 32 trial varieties. The presenters displayed 18 of these varieties and discussed color, gravities and size uniformity.

The 1,100 pounds of trial potatoes were planted May 20 at 10-inch spacing. The potato crop had been preceded with oats underseeded with clover and orchardgrass.

Penn State currently has more than 200 potato varieties in trials — 140 white varieties, 39 red and purple, 38 russets and long whites, and a few others.

The trial stock came from Idaho, Colorado State University, the University of Maine, and other institutions and private companies.

Mike Peck from Penn State’s Plant Pathology and Environmental Microbiology Department said a number of regional trials, including tests for yields, genetic work, late blight and the par-fry trials, are still to come.

Peck also said the USDA has approved Simplot Innate potatoes, which are late blight resistant, genetically engineered potatoes.

Unlike Roundup Ready corn, which had an outside gene added to the corn’s DNA, the traits in Simplot potatoes are developed from genes that are already in the potatoes themselves.

“I don’t know how the market will respond,” Peck said.

Simplot also has scab- and early blight-resistant potatoes in the pipeline, and two years of data on potatoes that will produce 30 percent more potatoes with 15 percent less water.

There are thousands of potato varieties to choose from, Peck said, but Extension narrows down the trial choices to try to find out what will grow best in Pennsylvania.

Robert Leiby, a crop consultant at Pennsylvania Co-Operative Potato Growers, discussed pests and weather management. Summer temperatures continue to increase, and this year was a particularly hot and dry summer.

“I think we need to think about this and how we grow potatoes,” Leiby said.

Ideally, potato pulp temperatures should be under 66 degrees when the tubers are pulled from the field. This year, Leiby and his team were measuring pulp up to 85 degrees at harvest.

The summer heat was also blamed for double sets of tubers, one large, deep set and a shallow, smaller second set.

“Potatoes don’t particularly care for the heat we’re seeing,” Leiby said.

Historically, Pennsylvania potato growers have not used refrigerated storage, but harvesting the potatoes in this heat is tricky.

North Carolina, Maryland and other Southern states have small windows to harvest potatoes for lasting storage and have learned to adjust to those windows.

Although planting later is one option, Leiby said late-grown potatoes are more prone to extensive Colorado potato beetle damage and blight.

Leiby said he wants to see more formed beds so potatoes won’t sit in standing water. The beds would also allow more heating and cooling options for the potatoes.

He also discussed the Snack Food Association trials on a farm in Chambersburg. The harvest was rained out this week, so they’ll be harvesting these chip varieties next week for review.

“We’d like to have an out-of-field chipper better than Atlantic, and we’d like to have a chip in storage better than Snowden,” he said.

As far as pests, Leiby said that he has seen thrips in potato fields over the last three years, and that it’s time to do a controlled spray when female Colorado potato beetles are laying eggs.

There’s an interval of five days to two weeks after those sightings before the beetles hatch. Once they are bigger than the initial hatched stage, it’s almost too late for an effective control.

As of the meeting, Leiby had not seen any late blight on commercial potatoes in Pennsylvania. This may be due to the hot weather, which slows down blight.

Leiby discussed two potato diseases, blackleg and dickeya. Blackleg rots a potato plant from the seed piece up, and causes stunting, wilting, chlorosis of leaves, necrosis of tissue, a decline in yield and the eventual death of the plant.

Dickeya, a pathogen related to the blackleg bacteria, is expected to cause growers problems in the future.

This bacterium was found in Long Island, New Jersey, southeastern Pennsylvania and points south during this growing season.

The first symptoms include poor emergence and wilt. The plants rot from the inside out, causing collapse and bacterial soft rot in some or all of the underground tubers.

Some tubers have latent infections that are not noticeable at harvest but develop symptoms later.

Leiby says it is fairly certain the bacteria can move from plant to plant in the soil. Tests last year on 23 samples that showed dickeya symptoms came up with 20 that were positive.

A national potato growers organization formed a committee in 2015 to track dickeya, and a doctoral candidate in plant pathology will be researching and collecting samples to catalog species of dickeya found in potatoes to confirm that it is the same pathogen in all cases. This research will take a couple years.

“It’s really being viewed as a national problem,” Leiby said.

He emphasized the need for clean seed potatoes. Growers should ask for the North American certified potato seed health certificate, which has the lot numbers and seed history for the previous five years, Leiby said.

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