There is a difference, says Harris, between tissue and petiole sampling. “These are often confused because I get calls from people who run tissue as a petiole or petiole as a tissue. Tissue is where we take the leaf blade, we run total nitrogen, and then we run P and K and other nutrients, and we do all of that prior to bloom. Tissue sampling is recommended between first square and first bloom. We have sufficiency ranges for those nutrients for that time period.

“With the petiole program, we take the stems, and we’re not running total nitrogen, we’re running nitrate nitrogen. We run P and K, and we run the phosphorus just to give us a guide on how it interacts with nitrogen. We start petiole testing at first bloom and then we go into the eighth week of bloom. They are very different systems, and if you take one and run it as the other, it won’t make much sense.”

Harris says he isn’t recommending that growers should petiole-sample every acre. It’s good, he says, for new growers and for growers who are planting on new ground. “We don’t have a lot of new ground, but we’re still pushing up pine trees in corners, and we’re trying to avoid a severe nitrogen deficiency.”

Petiole testing is especially good for organic nutrients like poultry litter to find out how much nitrogen is available and if you need to supplement or not, he says.

Harris says he believes one of the main reasons Georgia growers are having problems with potassium deficiencies is new varieties.

“New varieties fruit earlier and more intensely. Growth habits have a lot of implications for the uptake of nitrogen and potassium and the potential for potassium deficiencies.”

Rising fertilizer prices is another reason producers should be concerned about being as efficient as possible when applying fertilizer, says Harris.

“We’re at a crossroads with the petiole testing program,” he says. “Should we try and revise it and make it user-friendly or throw it out? I think instead of a 10-week program, we might want to go with a five-week program. One of the problems with a10-week program is that it can be real confusing. Maybe if we had two weeks between samples. And maybe we should tissue-sample at first square and just do four petioles — first, third, fifth and seventh week bloom. I do worry that if we go with a five-week program that’s not as complex a program, it won’t be as accurate.”

phollis@farmpress.com