JulieT asks advice on dealing with diseased plants:
“I purchased longevity spinach online a couple years ago advise from your book. It is wonderful and grows like crazy. Unfortunately my spinach recently became covered with black spots. What do you recommend? I pulled it out of that garden spot as I have other places that have not been affected as much.”
Some years are worse than others for disease issues. My general assumption is that the plants got too flooded or the air is too humid, or they are lacking in good nutrition.
Plants that are well-fed and less stressed seem to sail through disease. But plants that are weakened by stress do not. The disease organisms seem to work like clean-up crews, attacking plants that are already missing something or which are under stress.
The black spots are common – especially later in the year and in winter when plants are winding down and the weather is cool. When it’s warm and growth is active, they often outgrow problems. Later in the year, they tend to have issues.
Instead of trying to treat the problem by the elimination of a single disease-causing organism (i.e., whatever is causing the black spots), I would try to add /more/ organisms to the system. In the past I have treated sick squash vines by spraying them with a solution of unchlorinated water with a little yogurt or kefir in it, coating the leaves in the evening. The addition of the bacteria in the yogurt often wipes out the infection. Brewing and applying compost teas or adding more compost/humus to the soil around the plant may help as well.
The other prong of defense is nutrition. If I have plants that seem to suffer from spots or mold or weak growth, I will use a mineral solution as a drench to add nutrients fast. A good way to do this non-organically is with Peter’s plant food, Miracle-Gro, or, my main go-to, Dyna-Gro. Organically, just try compost tea.
There may also be an imbalance in the nutrients already in the soil. If nitrogen levels are too high, you get rank growth which is then attacked by insects and/or disease.
Just a few thoughts. I wouldn’t worry about trying to remove or destroy them. I would just add some life and see what happens. Even ignoring them might work. As the soil and weather conditions change in the spring, they may just grow back fine.
If they die, then that might just have been the wrong spot for them. Sometimes these things happen. I don’t fight them too much. Especially when we’re dealing with tropical plants during a cooler time of year.
As I write in Totally Crazy Easy Florida Gardening, I believe in growing the stuff that lives and letting Nature knock down the weaklings, unless I really, really, care about that particular plant.
I also just go ahead and compost them without worrying about the pathogen. Nature tends to balance things out just fine.