Black spots on live oak leaves/when prune
What’s causing these black spots live oak leaves? This is tar spot, a fungus that manifests as black, blotchy lesions on this tree’s leaves, which some may confuse for sooty mold. But if inspected closely, it’s not hard to distinguish the difference.
Sooty mold is very diffuse, forming colonies on the surface of the leaf, that can easily be wiped off with a little pressure. Tar spot develops into blisters, involving several cell layers of the leaf itself, so they don’t rub off.
Also, although tar spots may spread across the leaf, eventually creating what appears to be a single mass, they do begin as individual circles, often developing a yellow halo of dead tissue at their edges. Sooty mold spreads across the surface to create a more uniform pattern. Although it may appear to be quite concerning, tar spot is rarely worth worrying about. It can be spread by wind, or more commonly, by water splashing on the leaves, so it usually appears at times of year when temperatures are cooler and the air is humid.
To combat this issue, be sure to rake up and toss all leaves from affected trees as they fall, to remove the source of spores before new leaves grow.
February weather is very unpredictable: hot, then cold; sunny, then cloudy. Warm days tempt us to prune: but it’s best to wait: pruning woody perennials encourages new growth, which will be tender and extremely susceptible to any upcoming frosty weather. For now, try to be patient, working in conjunction with your plant’s natural rhythms. For a way to scratch that spring itch, consider planting some winter annuals to add color amongst the bare spots. But resist the urge to purchase any warm weather annuals or tropical plants that start appearing in nurseries this time of year. Although the air might be warm enough for these plants, our soil won’t be until day-time temps begin to stay in the 80’s. And once our nights begin to stay in the 70’s, you can direct-sow seeds of warm-weather spring flowers like Zinnias, Cosmos, and sunflowers.
Although we still have some quite cool temperatures ahead, it won’t be long before our lawns start to show new growth (if they even went completely dormant at all), which might make us think it’s time to fertilize. But early in the season, turf is just starting to wake up, and it isn’t yet ready to take up all the nutrients that you may apply.
Your lawn will make better use of those nutrients if you wait until it’s actively growing, which for us in Central Texas is May, at the earliest. A good rule of thumb for lawn fertilization is to apply on the major summer holidays of Memorial Day, Independence Day, and Labor Day, being sure not to fertilize prior to rain, to prevent runoff into storm drains.
Most of us are overrun with winter weeds right now, so what’s the best way to deal with them? The best answer is to pull them, if that’s at all possible, and if not, to spot treat, rather than broadcast. This not only protects the environment, but also your lawn.
Many herbicides can actually damage your turf at this sensitive time, if they aren’t completely dormant. If you spot treat with an herbicide, be sure to watch that part of the lawn for any slow recovery as the rest of the lawn begins to green-up. If you notice any damage, take note, so that you don’t cause similar problems next season.
Pre-emergents can be effective, if applied at the proper time, which is challenging, now that our climate is no longer as reliable, with larger swings in temperature making it harder to gauge weed seed germination timing.
