Autumnal Travails of Deciduous Trees
It is fall. The calendar tells me we have passed the autumnal equinox, and the days are definitely getting shorter. The sun sets one to two minutes earlier each day, and rises one to two minutes later each day. We lose almost fourteen minutes of sunshine from our days this week. I'm alright with that, I love fall. Welcome fall!
If you are from somewhere else you probably see the weather in San Diego as more or less a seamless continuity of sunshine, no rain, and pretty ambient weather. Granted, we don't have frost on the pumpkin, hay being put up in barns, or leaves turning scarlet, orange, yellow, and russet hues. But we do have our own ways of marking our seasons.
For me one of our sure sentinels of fall is the emergence of the orb spiders in the garden. Seemingly from out of nowhere webs appear every morning, and colorful and ferocious looking arachnids take their places in the centers of those dream catchers.
Accompanying and enhancing the orb spider's webs is the arrival of morning dew, and the return of fog. Usually around the first or second week of September, we have heavy dew, and oh what that does for the beauty of those webs. There's nothing better to me than a walk through the garden in the early morning with a hot mug of coffee tending to the quotidian tasks, and happening upon a glistening gossamer display in that rare morning light. The direction and feel of the breezes changes in September as well. The very air changes. The feel of it on my face, the moisture, the scent of nature's breath whispers the changes in the air. Living in San Diego and being outdoors as long as I have, you recognize and love the subtleties of our seasonal changes.
One of the negative visual conditions of autumn in these parts is how bad things can look in the garden. The hot, drying Santa Ana winds of the most recent pressure changes were hard on our plants. It was cooling, we had rain, it felt like fall....then wham! We feel the Sirocco blasts of desert heat and desiccating winds burning leaves, buds, flowers, and seedlings. I wish I had put shade cloth over my 7 flats of vegetable seedling trays. My tender little seedlings became crispy critters in a matter of hours. Oops, I'll have start over again.
About this time each year I receive myriad questions and comments from folks about how really awful their fruit trees look. For the citrus, leaf miners have tunneled through leaves making them look shriveled and pathetic. Bug problems tend to reach a crescendo about now too. It can be really hideous looking, and many people will have 4-5 different pest issues on the same tree, all of them at their worst. One of the best things you can do is flush the trees with cool fresh water. Be careful about spraying leaves with the first blast of 150 degree water from a hose that has been baking in the hot sun, you can easily cause thermal burns. Wash away all the dust. Spray above and below the leaves, and don't forget to spray down the branches, twigs, and trunks of citrus. Brown scale, soft scale, and mealy bugs can be a huge problem on the actual woody parts of your citrus trees.
Citrus trees do not really ever need pruning in the traditional sense, but will often benefit from a gentle and deft hand at thinning. Don't confuse these two concepts. Thinning is the very careful removal of leaves and small twiggy areas where there is a lot of density. Thinning allows better air circulation and light penetration, which really helps keep pest populations down. If things are really bad, on a cool morning or evening spray some horticultural oil on the trees to smother the clinging pests.
How are your stone fruits and other deciduous fruit trees looking about now? If they look like ten miles of torn up road, smile. Take heart, because you are not alone. Bearing all that fruit isn't easy. Pests are lurking everywhere: fungi, viruses, bacteria, and insects that all want to take out your trees. Ohhhh baby, baby, it's a wild world! And there are new challenges all the time. It really is a miracle that we get food from our plants at all.
Have you ever run a marathon? Even if you are fit, in good health, and well conditioned, the rigors of twenty-six miles will show on you by the finish line. Here's the thing, your trees have run the horticultural equivalent of a marathon and we are at mile twenty-five. And last week, the 25th mile was made all the more arduous by the heat and dry wind of high pressure systems. Your trees have earned the right to look bad.
Trees are already beginning to drop leaves. Bacteria and fungi problems have done about all the damage they can do, and your leaves, if they aren't dropping yet, look like heck. That's alright. Don't really lose any sleep over it. But there are things you can do to make next season its best:
1) Let the leaves fall, but don't let them remain there. As soon as all the leaves have dropped, rake them and put them in your greens container for pick up. Unless you are an experienced composter using "hot" techniques, don't try to compost these leaves yourself. If left on the ground or cool composted, bacteria and fungi from the old leaves can re-infect your trees next year. Let the city hot compost those leaves for you.
2) You really MUST do dormant spraying once the trees are defoliated. Most gardeners wrongly assume dormant spraying is only about peach leaf curl. Peach leaf curl is only one of the diseases that can be prevented or diminished through dormant spraying. Bacterial leaf spot, shot hole fungus, boytritis grey mold, brown rot, rust, powdery mildew, and many other fruit tree problems can be reduced or eliminated by dealing with these issues in winter. It is also important to use an oil spray in winter on the trunks, branches, and twigs to kill off eggs, larvae, and adults of quite a few destructive insects.
3) Just when it feels like fall is in the air, we will be hit again with Santa Anas. If the days are hot, and the wind desiccating, water the night before an expected Santa Ana condition. This is especially important with citrus and avocados. Water the night before, so hot soil and added moisture don't cause a phytophthora outbreak.
4) Mulch! Mulching with fresh mulch prior to bud break will help prevent re-infestation of trees with fungal and bacterial diseases becoming airborne. Mulch is also the single most helpful measure one can take to prevent Phytophthora killing your fruit trees. This is especially true with avocados.
If your trees look awful right now, take heart. Those nasty leaves will drop, and you will have a brand new chance at healthy trees next spring. Hang in there, and happy gardening.
If you are from somewhere else you probably see the weather in San Diego as more or less a seamless continuity of sunshine, no rain, and pretty ambient weather. Granted, we don't have frost on the pumpkin, hay being put up in barns, or leaves turning scarlet, orange, yellow, and russet hues. But we do have our own ways of marking our seasons.
For me one of our sure sentinels of fall is the emergence of the orb spiders in the garden. Seemingly from out of nowhere webs appear every morning, and colorful and ferocious looking arachnids take their places in the centers of those dream catchers.
Accompanying and enhancing the orb spider's webs is the arrival of morning dew, and the return of fog. Usually around the first or second week of September, we have heavy dew, and oh what that does for the beauty of those webs. There's nothing better to me than a walk through the garden in the early morning with a hot mug of coffee tending to the quotidian tasks, and happening upon a glistening gossamer display in that rare morning light. The direction and feel of the breezes changes in September as well. The very air changes. The feel of it on my face, the moisture, the scent of nature's breath whispers the changes in the air. Living in San Diego and being outdoors as long as I have, you recognize and love the subtleties of our seasonal changes.
One of the negative visual conditions of autumn in these parts is how bad things can look in the garden. The hot, drying Santa Ana winds of the most recent pressure changes were hard on our plants. It was cooling, we had rain, it felt like fall....then wham! We feel the Sirocco blasts of desert heat and desiccating winds burning leaves, buds, flowers, and seedlings. I wish I had put shade cloth over my 7 flats of vegetable seedling trays. My tender little seedlings became crispy critters in a matter of hours. Oops, I'll have start over again.
About this time each year I receive myriad questions and comments from folks about how really awful their fruit trees look. For the citrus, leaf miners have tunneled through leaves making them look shriveled and pathetic. Bug problems tend to reach a crescendo about now too. It can be really hideous looking, and many people will have 4-5 different pest issues on the same tree, all of them at their worst. One of the best things you can do is flush the trees with cool fresh water. Be careful about spraying leaves with the first blast of 150 degree water from a hose that has been baking in the hot sun, you can easily cause thermal burns. Wash away all the dust. Spray above and below the leaves, and don't forget to spray down the branches, twigs, and trunks of citrus. Brown scale, soft scale, and mealy bugs can be a huge problem on the actual woody parts of your citrus trees.
Citrus trees do not really ever need pruning in the traditional sense, but will often benefit from a gentle and deft hand at thinning. Don't confuse these two concepts. Thinning is the very careful removal of leaves and small twiggy areas where there is a lot of density. Thinning allows better air circulation and light penetration, which really helps keep pest populations down. If things are really bad, on a cool morning or evening spray some horticultural oil on the trees to smother the clinging pests.
How are your stone fruits and other deciduous fruit trees looking about now? If they look like ten miles of torn up road, smile. Take heart, because you are not alone. Bearing all that fruit isn't easy. Pests are lurking everywhere: fungi, viruses, bacteria, and insects that all want to take out your trees. Ohhhh baby, baby, it's a wild world! And there are new challenges all the time. It really is a miracle that we get food from our plants at all.
Have you ever run a marathon? Even if you are fit, in good health, and well conditioned, the rigors of twenty-six miles will show on you by the finish line. Here's the thing, your trees have run the horticultural equivalent of a marathon and we are at mile twenty-five. And last week, the 25th mile was made all the more arduous by the heat and dry wind of high pressure systems. Your trees have earned the right to look bad.
Trees are already beginning to drop leaves. Bacteria and fungi problems have done about all the damage they can do, and your leaves, if they aren't dropping yet, look like heck. That's alright. Don't really lose any sleep over it. But there are things you can do to make next season its best:
1) Let the leaves fall, but don't let them remain there. As soon as all the leaves have dropped, rake them and put them in your greens container for pick up. Unless you are an experienced composter using "hot" techniques, don't try to compost these leaves yourself. If left on the ground or cool composted, bacteria and fungi from the old leaves can re-infect your trees next year. Let the city hot compost those leaves for you.
2) You really MUST do dormant spraying once the trees are defoliated. Most gardeners wrongly assume dormant spraying is only about peach leaf curl. Peach leaf curl is only one of the diseases that can be prevented or diminished through dormant spraying. Bacterial leaf spot, shot hole fungus, boytritis grey mold, brown rot, rust, powdery mildew, and many other fruit tree problems can be reduced or eliminated by dealing with these issues in winter. It is also important to use an oil spray in winter on the trunks, branches, and twigs to kill off eggs, larvae, and adults of quite a few destructive insects.
3) Just when it feels like fall is in the air, we will be hit again with Santa Anas. If the days are hot, and the wind desiccating, water the night before an expected Santa Ana condition. This is especially important with citrus and avocados. Water the night before, so hot soil and added moisture don't cause a phytophthora outbreak.
4) Mulch! Mulching with fresh mulch prior to bud break will help prevent re-infestation of trees with fungal and bacterial diseases becoming airborne. Mulch is also the single most helpful measure one can take to prevent Phytophthora killing your fruit trees. This is especially true with avocados.
If your trees look awful right now, take heart. Those nasty leaves will drop, and you will have a brand new chance at healthy trees next spring. Hang in there, and happy gardening.
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