January came and went, and for once, time seemed to drag. Apart from political and COVID misery, the month opened with gray, chilly weather, powdery mildew, and an episode of red tide. Not a great start for a happy new year.
Powdery mildew first appears as white, somewhat circular splotches on the top sides of leaves. It looks a little like they have been sprinkled with flour or talc. Yellowing, browning, and death of the leaf may follow. Powdery mildew, a true fungus, flourishes with cool nights combined with high humidity and warm days. This time of year we tend to have heavy dewfall, and even fog. If I were growing vegetables this year, I most likely also would be dealing with downy mildew, a socalled "water mold," which likes the same conditions.
Since crowding, combined with shade and moisture, makes powdery mildew worse, it showed up mainly on large clumps of dune sunflower, Helianthus debilis growing around some palms and large shrubs in the front yard, and on the near-prostrate rosettes of Elliott's aster.
I am letting the Elliott's aster deal with the mildew on its own. The rosettes collect moisture every night and early morning. I probably couldn't get it completely eradicated even with a regular spray schedule, and since I avoid pesticides, I'm not spraying it at all. Since this is a recurring event, I expect the asters to grow out of the problem once the drying winds and sunnier days of March roll in.
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Powdery Mildew on Elliott's Aster |
There are 3 subspecies of Helianthus debilis in Florida. My plants, originally obtained from native plant sales, are predominantly the east coast dune sunflower, Helianthus debilis subsp. debilis. The species hasn't been vouchered in Collier County, but I have seen it growing on the dunes. Since walking on the dunes is a serious no-no because it is so destructive, I can't say for sure what subspecies they are. The plants in our yard are both mounding and somewhat vining. They root easily at the nodes. The leaves are roughly triangular, and shaped like arrowheads with a large base. They have a sandpapery texture. The petioles are long, and the leaf margins vary from entire to noticeably toothed. The stems range in color from green to maroon, and are also somewhat rough to the touch. The sinuous quality of the stems makes the plant fun to draw.
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Helianthus debilis Stem with Opening Head |
Flower heads are an intense yellow. Just before the sun sets, they can take on a slightly luminous quality. The plants are evergreen here, and bloom all year. Butterflies and moths visit them, though they are not favorite nectar plants. A variety of bees, wasps, and other small pollinators are more common visitors in our yard. Mourning doves like to shelter under them, and no doubt eat the seeds.
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Dune Sunflower Habit |
Apart from its eagerness to overrun the entire yard, Helianthus debilis is a great garden plant. Its colorful blooms and bright foliage enliven the yard. Like Gaillardia, a clump of dune sunflower just cheers up the scene. Its semi-vining stems will cascade prettily over the sides of a large pot. The hidden branches of a large, old clump become infested with whitefly and mealy bugs over time. Otherwise I haven't noticed any insect problems, and no disease troubles other than the seasonal mildew. The plant is extremely drought tolerant. I never water it unless it is in a pot.
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Helianthus debilis |
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Officials like to say that red tide is a natural phenomenon. They're right - to an extent. These algal blooms can be caused by an upwelling of nutrients from the ocean floor, triggered by large storms, temperature swings, changes in salinity, and so forth. They normally occur here when the weather is warm - from August to November.
But red tides have become more persistent in the past 5 or so years, exacerbated by humans. The period from the summer of 2016 through the winter of 2019 was particularly disastrous for southern Florida. Heavy rains forced the Army Corps of Engineers to make record-breaking discharages of fresh water from Lake Okeechobee. The fact that the earthen levee around Okeechobee is obsolete and can't stand the pressure of elevated water levels has been known for decades, but the political will to do anything about it has been lacking. Fresh water itself is a pollutant in brackish and saline ecosystems. Discharges from the lake weren't only fresh water, but fresh fertilizer-laden water.
Lake Okechobee feeds the Caloosahatchee River on the west coast, and the St. Lucie river on Florida's east coast. Discharges to the west contributed to an existing red tide in the Gulf. "Our" red tide here on the southern Gulf coast is caused by a population explosion of a dinoflagellate called Karenia brevis. Karenia brevis can't survive in fresh water, but while the west coast was coping with beaches strewn with dead fish and marine mammals, and more, the east coast sustained equally disastrous consequences due to a nutrient-fed bloom of blue-green algae. Some places, like Sanibel Island, near the mouth of the Caloosahatchee, got the worst of both worlds. Sanibel even had to deal with a 21-26 foot-long dead whale shark that washed up on one of its beaches. (Reports on the size differ). Florida lost numerous dolphins, sea turtles, and approximately 13% of the manatee population.
Lake Okechobee feeds the Caloosahatchee River on the west coast, and the St. Lucie river on Florida's east coast. Discharges to the west contributed to an existing red tide in the Gulf. "Our" red tide here on the southern Gulf coast is caused by a population explosion of a dinoflagellate called Karenia brevis. Karenia brevis can't survive in fresh water, but while the west coast was coping with beaches strewn with dead fish, dead marine mammals, and more, the east coast sustained equally disasterous consequences due to a nutrient-fed bloom of blue-green algae. Some places, like Sanibel Island, near the mouth of the Caloosahatchee, got the worst of both worlds. Sanibel even had to deal with a 21-26 foot-long dead whale shark. (Reports on the size differ). Florida lost numerous dolphins, sea turtles, and approximately 13% of the manatee population.
The state sustained millions of dollars in lost tourist revenue as well as cleanup costs. Fisheries and related business such as marinas, fishing guides and boat rentals also suffered catastrophic losses. With no income tax, Florida depends heavily on tourism revenue and taxes, and the blow was bad enough finally to jolt some political actors awake. It's too bad that it takes a massive pocketbook issue like this to speed up significant corrective activity. One would think that degraded ecosystems and lowered quality of life would be enough.
Karenia brevis produces a neurotoxin that builds up in the food chain. Wind causes it to be aresolized, and many people living near the coast, including me, end up with real respiratory distress from red tides. Some people even need to be hospitalized. It's quite possible that it contributes to the deaths of marine mammals and sea turtles, which all breathe air. This January hundreds of dead fighting conchs washed up on one Marco Island Beach. If you think dead fish smell bad, wait until you get a whiff of rotting mollusks! Our canal turned a nasty reddish-brown color, and the fish, first catfish and mullet, started floating belly-up.
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Red Tide in Our Canal |
After a few weeks' absence, red tide is back in the region, if not in our own backyard. The bloom gets blown or carried out by tides into the Gulf. When we get westerly winds it blows back in. This time around it is affecting fish-eating birds such as royal terns, cormorants and pelicans, along with fish, mollusks and sea turtles.
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The cooler weather this fall and winter has given us a bit of seasonal color. Some years the Virginia Creeper stays mostly green, but this year my neighbor's vine, creeping through the slats in our fence, sported lovely reds and violets. It's a pretty vine, even green, but it is too rapacious for most landscapes - especially small ones. Her yard crew pulled it out shortly after I made my sketch, but it will pop up again.
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Virginia Creeper - Parthenocissus quinquefolia |
In the meantime, dune sunflower, other seasonal flowers, and visits by migratory birds keep the gloom and doom away. I even saw a leucistic grackle, something I'd never heard about before. The feathers on its head were startling white. I haven't seen it since.
