Garden Q&A: Why are my annuals withering?
Q: A few of my annuals are withering. The leaves just collapsed and wilted. When I water, nothing recovers. Are they a lost cause?
A: This sounds like root rot, unfortunately, which would indeed mean that those individual plants are a lost cause. Wilting can be caused by under-watering and dry roots or over-watering and soggy roots. When the roots fail to function properly, whether due to dryness or when excess water drives air out of the soil, they can’t supply the top growth with moisture, so the foliage wilts.
How do gardeners tell the difference? Ideally, you’re monitoring plants periodically for watering needs before wilting ever happens, but everyone has been caught off guard by a wilting plant now and then. Before you reach for the hose, though, feel the soil.
Monitoring depth will depend on the plant involved and where it’s growing. For annuals, I’d use at least a full finger’s depth for plants in the ground, and at least an inch deep for plants in pots. If the soil feels somewhat dry to the touch at that depth, watering is probably needed, especially if the plant is wilting or droopy. If damp to the touch, then watering is not likely needed, and adding more water might push the plant over the point of no return. (Though, honestly, that’s usually the case when a plant is wilting in soil with plenty of moisture. Root rot is too advanced at that point.)
Nothing can cure root rot once it sets in. The soil doesn’t need to be sterilized, though, and take some small consolation that these pathogens are opportunists – they take advantage of plants under stress, often from over-watering, and the microbes can coexist with healthy plants whose root systems are vigorous and thriving in the conditions they prefer. For annual bedding plants, often it’s just centered around having good drainage and not being watered when they aren’t dry.
Unfortunately, a wide array of popular annuals are vulnerable to root rot if kept too wet, such as flowering vinca, petunia and their calibrachoa cousins, fuchsia, marigold, pansies, dianthus (carnations) and celosia.
Q: My lawn is developing brown patches (not large areas, just scattered). Is this a disease, and what fungicide do I use?
A: It can be difficult to diagnose turf diseases from symptoms of leaf blade bleaching or die-off alone. While I can’t rule out early-season suspects like dollar spot, dieback from other diseases can look very similar. This is especially the case when fungal mycelium (the actual fungal tissue, which can look somewhat fuzzy or threadlike) is not visible on the surface of the grass blades.
You can look for mycelium just after a dewy morning, foggy day, or after rain, since it might disappear during drier, warmer, or breezier weather. The appearance of the mycelium can help differentiate some of the diseases whose damage is very similar.
Fungicides are seldom warranted for home lawns. Few of them will treat these or other lawn fungal infections, and several among them require application by a certified pesticide applicator, if they are restricted-use chemicals. Most well-trained lawn care companies should have one or more certified applicators that can apply pesticides, plus help to make a more concrete diagnosis before determining what steps to take.
Even when their use is warranted, fungicides are preventative tools only, helping to prevent infection on still-healthy grass foliage. They cannot cure existing diseases.
Actions like adjusting irrigation use, testing soil and fertilizing more (within reason and the Maryland law restrictions), or aerating or dethatching (though tall fescue doesn’t form thatch, so this depends on the species makeup of your lawn) can all make an impact on reducing disease outbreak vulnerability in the future. Information about these and other recommended lawn care practices can be found on our Lawn Care and Maintenance web pages.
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.