Spring Training

Baseball spring training is well underway, and there's also been some spring training for mango season here in north Sarasota. All thanks to Rosie, my Rosigold mango, not to be confused with the well-traveled Rosie who now lives with Mr. and Mrs. Colorado.

Rosie was bought at the MRFC's 2012 tree sale, and stands a little over six feet tall. In the crazy warm weather last fall, she bloomed and managed to hang on to several mangos. They were going along fine, but seemed to stop growing after the near-freeze on January 24 ushered in a stretch of cooler weather. I picked one on the 31st, just in hope that I could say I grew a January mango, but it never ripened.

So I wasn't very optimistic about the one I picked early in March. It sat on the shelf for a long time. Lemons and loquats joined it briefly, before moving on to their culinary destinies. Finally, a patch of anthracnose on its skin started to spread, and maybe it didn't feel quite so firm, so on March 23 I decided to give it a try.

RBI for Rosie, it was a pretty good mango! Firm, but sweet and very flavorful. Best I've had since, oh, last fall.
 

Regular season baseball starts in a week, but regular season mangos are farther off. At least there's a little more to come for now. Here is another of Rosie's, that will be ripening on the shelf by the time you read this.

And Rosie's all caught up in the frenzy of mango-making going on around here, so she's making more fruit too.

As long as I'm showing off mango photos, I can't resist closing with this shot of three on the east side. From the left: Glenn, Coconut Cream, and Mallika. With oak trees to the east and west, they have to get by on a few hours of midday sun. But they have grown well--- well enough to earn the green light to produce a few fruit this year if they can manage it.

Hold The Copper

Mango trees are blooming like crazy right now. They are mighty easy trees to grow, at least for those within a few miles of the coast, but they do have one Achilles' heel--- their vulnerability to fungi. Anthracnose and powdery mildew are the big two, but there are also scab, leaf spot, and Verticillium wilt. An extensive collection of photos of these uglies, taken by Scot Nelson of the University of Hawaii at Manoa, can be found at growables.org.

The big two can attack newly emerging panicles, flowers, and young fruit, leading to the disappointing fruit drop that often follows a promising start. What's a dooryard grower to do?

Prevention is always the best place to begin, and good basic practices include selecting anthracnose-resistant varieties and growing in sunny locations where the trees can dry off faster. Also, prune to keep the interior open to airflow, again to minimize fungus-friendly moisture. This carries the added benefit of letting more light reach the lower branches, helping the grower to keep the tree shorter and bushier.

When fungal problems do appear, sulfur and copper are the standard fungicidal options. One application when the panicles are half-size and a second about 10 to 21 days later is a typical recommendation. Elemental sulfur is non-toxic, while copper definitely falls in the toxic category, and can persist and accumulate. Sources are inconsistent concerning the relative effectiveness of these against each of the big two fungi, but the general impression I get is that sulfur is effective against powdery mildew but perhaps not so much against anthracnose. The "safe" recommendation seems to be copper or a combination of the two fungicides.

I reckon there is sulfur in my future. As for copper, never say never, but I'll have to be dragged there kicking and screaming.

For now, I'll make use of the twin luxuries that dooryard growers have and commercial growers don't. First, our fruit can be ugly, as long as it tastes fine. And second, we can fail without going out of business. So this season I'm trying a biological approach using a well-known fungus-fighting microbe, Bacillus amyloliquefaciens. It comes in different strains, and strain D747 is approved for use against papaya anthracnose in Hawaii. At least one strain, DGA14, has worked against mango anthracnose on fruit surfaces in the laboratory.

Last year I obtained some D747 from a large supplier of ag products for the southern region, and I've been spraying it on my mango trees during this flowering season. Of course the great and sometimes insurmountable challenge of horticultural science is to ferret out which of the dozens of variables involved are actually having an effect, so I don't expect anything definitive from my limited sample. But if my larger trees all hold some fruit this year, B. amyloliquefaciens will get a longer look. If not, then there's Bacillus subtilis...

The Latest Commercial Banana Disaster

I hope everyone enjoyed Betty Kearns' article and photos in the March MRFC newsletter as much as I did. In January Betty and Pete toured a banana plantation in Costa Rica, including its ultra-efficient processing facilities preparing the fruit for export. If you missed Betty's article, do catch it in the MRFC archive here.

Bananas were again a topic, this time for the second hour of the March 10 Diane Rehm show on NPR, available on iTunes or for direct download here. The title was “The Uncertain Future of the Banana”, and featured scientists Robert Bertram of the USAID and Randy Ploetz of TREC, as well as Dan Koeppel, author of Banana: The Fate of the Fruit That Changed the World.

The program's headline story is the latest version of Panama disease, the soil-borne fungus Tropical Race 4. TR4 refers to the fungal strains of Fusaium oxysporum f. sp. cubense that cause Fusarium wilt in Cavendish cultivars grown in tropical conditions. In addition to the normally fungus-resistant Cavendish, TR4 affects a number of varieties of dessert and finger bananas, and is devastating commercial operations wherever it appears. It's been detected traveling halfway around the world on muddy boots, and its spread to all major banana-growing areas is considered inevitable.

There is no cure for TR4, and drastic techniques such as sterilizing the soil with methyl bromide (not a favored Druidic practice) provide only a couple of years of production before the soil is recolonized worse than before. Leaving land fallow is useless, as TR4 can survive below ground for decades. Conventional selective breeding for resistance looks hopelessly difficult for the seedless domesticated banana. Dr. Ploetz holds some hope for genetic engineering methods, but only time will tell whether they bring more rapid progress for bananas than for our beloved citrus.

The program has some interesting discussion of bananas and their commercial industry. Around 400 million people rely on bananas as a primary source of calories, and about the same number derive a significant part of their livelihood from its cultivation. In contract to the large-scale production methods of the Americas, around 95% of bananas in Africa are produced by small farmers.

The panelists agreed that Cavendish is not a great-tasting banana. Indeed in India, which has 600 varieties of bananas, it's called the “hotel banana” since only tourists want to eat it. It's inferior to the Gros Michel, which was the dominant commercial variety until the 1950's when an earlier edition of Panama disease destroyed its commercial value. Tasty or not, the Cavendish is the most productive commercial variety, accounting for half the world's banana production, and now it's on its way out.

The panelists had differing speculation about the future of the banana industry. Dr. Ploetz doubts that American consumers will accept higher prices for unfamiliar and less beautiful bananas, but Dan Koeppel was more optimistic. I am more in the latter camp, agreeing with Koeppel that just as apples are now accepted in several commercial varieties, bananas can diversify and still keep a space--- perhaps a lesser one--- on grocery store shelves. The major banana companies are well aware of the educational challenge before them: teaching Americans that many varieties need to be well-browned before reaching their optimal flavor. Enormous amounts of Cavendish are discarded from stores simply because they have a few brown spots.

Is TR4 a worry for us dooryard growers? Not much, as there are still plenty of good-tasting TR4-resistant varieties to choose from. Only in the kilos-per-hectare commercial world does “productivity” matter so much. The question is whether bananas will become one of the “rare” fruits we've named our club for.

The Magnificent, Or Perhaps Puny Seven

Ever since I let a dozen or so papaya plants flood out in the summer of 2013, I've been wanting to do the papaya thing right. A few random ones are still around, growing in too much shade, but last year I accumulated some better selections. I managed to start two broadleaf papayas from Berto Silva's seeds. At the Suncoast Tropical Fruit and Vegetable Club's fall sale down in Nokomis, I bought a half-dozen small Sunrise papaya starts, together with a pair said to be from seeds brought back from Costa Rica. On the back porch, in some tasty potting mix, they grew well through the fall and even in the warm winter.

As for their planting site, it started as a big hole in the ground, in the middle of some extra garden space in the northeast quadrant. I dug it last fall, with some finishing help from my able horticultural colleague, MRFC Secretary Josh Starry. I should have take some photos, but didn't, so you'll have to take my word for it that it was close to six feet deep and twice that across.

Some of the excavated soil went to a semicircular mound half-enclosing the pit. The bulk of it went somewhere else, but that's a topic for another day.

We cleared out an area of overgrown junk banana plants in the southwest grove, producing two of these truckloads of bananastuff. Josh used the machete--- which somehow seems to be quite a bit sharper when he wields it than when I do--- to chop the stalks into sections. They went into the pit, along with a couple of piles of pulled weeds and sod that had been composting for a while.

A layer of tree-pruner mulch went on the mound, and extra-heavy layers on both sides of it and atop the pile of bananastuff. As the rainy El Niño winter progressed, the mulch wove itself into a mat and started its breakdown process. Meanwhile the papaya plants graduated from the porch to the outdoors, first to a part-shaded area, then to a sunnier spot to toughen up for their big day.

March is a good planting month, and I wasted no time. On the 1st I planted the broadleafs, Costa Ricans, and three of the Sunrise's at five-foot spacing on the mound. Here you can see one of the broadleafs and one of the Sunrise's after planting. The rest of the Sunrise's will likely go to our May tree sale if they aren't needed as replacements.

As you can see in the next photo, the bananas haven't given up. They keep sending stalks up from the pit. Periodically I saw them off to compost in place, after a moment of appreciation for their service of nutrient recycling.

The seven papayas looked stout and vigorous in their containers, but alarmingly puny after planting in the great outdoors. A meditation to Ma'am Gaia couldn't hurt. Positive requests seem to have better prospects--- and less chance of backfiring--- so I asked that the evil ring-tailed demons of the forest find excellent foraging there all through the spring, and feel no need to rampage through my property pawing young trees and papaya plants. I also double-staked each of the new plantings. Ma'am Gaia sometimes grants our wishes and sometimes not, but she's got no time for those who do not make the effort.