Management key to large lemons

It's well known in the industry that an early, large lemon is valuable. Mike Weatherwax, after over 25 years in the Yuma, Ariz., citrus business knows how to get that lemon: Give the trees the inputs they need.

Weatherwax Farms is a grove leasing and management company that has learned achieving that early, large fruit requires more water and nutrients than is commonly understood.

“There's a tremendous demand for large-size fruit,” Weatherwax says, Last August large fruit was demanding $37 per box because there was little available.

Weatherwax manages about 700 acres of lemons and has an ownership stake in about 50 of those acres.

Each year is a new growing regime, says Weatherwax in his effort to get those large lemons.

What does not change is the conditions where most of Weatherwax' lemons are planted, on the very sandy Yuma Mesa soils.

“Basically all the sand does is hold the tree up,” he points out. It holds little water and is definitely nutrient deficient.

Weatherwax irrigates every eight days in the summer. Fourteen days is more typical. It is all flood irrigated. He will use up to 15 acre feet of water during the year. Nine is more typical.

He would like to drip-irrigate, but it is costly to convert mature trees and their expansive root systems to drip.

Besides the high cost of heavy irrigation, there is the danger of phytophthera blooming in the sand. Weatherwax turns that to an advantage by using fungicides that also provide a nutrient component. Products such as Nutrifite or Phosgard provide some nutritional value as well as guarding against fungi.

He would rather treat for phytophthera than to short his trees on water.

“Phytophthera — you've either got it, or you're going to get it,” he says.


“I have the trees on a program where they get a fall fungicide application and a spring application,” Weatherwax says. He notes that it is important to maintain this type of program continually, both for phytophthera control and for plant nutrition.

He has followed this program for years, and he believes it helps produce larger fruit on a regular basis.

“The other thing I started doing 10 to 12 years ago was messing with the good bugs to build the soil,” he says.

He admits some may consider the products he uses as snake oil. He has tested many products over the years and has incorporated only the proven ones in his program.

Currently he is using materials that have humic acid and a “biological package” of bacteria and other organics that help build the organic content of his soils. He gets them from a local independent manufacturer and applies 30 gallons per acre per year.

“I put on two applications a year. Spring and fall.” These custom mixes are water-run solutions.

It takes years to build good soil out of sand, but he believes it pays off with healthy trees and crop uniformity. A spin-off benefit is that the organic ingredients help counteract the salt in the water supply.

These organic humic acid blends are not nitrogen-rich, and Weatherwax continues to use chemical fertilizers. They are balanced N-P-K fertilizers custom blended for his ranches by United Agri Products, and he applies them regularly and often rather than a few times per year.

“I spread smaller applications over several times a month,” he says. In the fall, those custom blends will be higher in nitrogen, and in the spring they will be more balanced with higher levels of potassium and phosphorus.

“In the fall, NPK. In the spring KPN,” he says.

He watches the tree growth to gauge nutrient needs, taking special note of leaf size, which he relates to fruit size. He also watches blooms in relation to leaf flushes, and feeds trees accordingly.

Nitrogen care

He believes giving nitrogen to trees that are having a flush of growth is counterproductive if the flush is before the bloom. So he will use fertilizers that are lower in nitrogen in that case. If the bloom occurs before the flush, he will use a product with more nitrogen in it.

“Typically, I'll start with my first shot of fertilizer in January,” he points out. Over the years he has noticed that a warm January will start the trees on a growing trend and he will feed that. If it is a cold winter, he probably won't fertilize in January.

He typically does not fertilize lemons during the summer — through all of July and August, and very little in September.

Weatherwax manages groves of different ages, he has learned mature trees respond differently than young trees to nutrition and varies his treatments accordingly.

“I've been getting very aggressive with foliar spray,” he notes. He will use foliar blends to fill in between the water-run applications, mostly to add micronutrients. In addition, he will add more nitrogen to his foliar sprays than is usual.

One crucial time in the life of a lemon is during the bloom cycle, and Weatherwax has experimented with foliar applications at different times to improve sizing and earliness. Oftentimes the fruit needs immediate attention and foliar gives him that option.

Weatherwax says that the upshot of extra nutritional inputs and irrigations costs an extra $100 per acre, average, on his lemons.

Being aggressive can be expensive, he admits. “But if you get the results, how expensive is it?”

Weatherwax says his growing costs are about $1,100 to $1,200 per acre.

“But if you jump one size of lemon you can make that up real quick,” he says. For example, going from a 140 count to a 115 can bring an extra $7 per box.

Consistent producers

And, Weatherwax says his groves are consistent producers. Last season was an odd-weather year and many growers experienced as much as a 50 percent drop in lemon volume. He says his worst grove was off by about 10 percent.

“I'll swing with the weather trends like everyone else, but my swings are very subtle,” he says.

Weatherwax also is aggressive in some other aspects. He thinks pruning is a big part of producing larger fruit.

“Keep the trees opened up, set the fruit on the inside,” he says. “The inside fruit seems to size, and the quality is consistently better.”

“We'll try anything that makes sense,” he says, but first talks with others before trying it and then conducts replicated tests before widespread use.

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