Knowledgebase
Eastern Redbud Sapling with some leaves being eaten and others with dried out tips #839060
Asked July 05, 2023, 12:12 PM EDT
Baltimore County Maryland
Expert Response
Hi,
The pictures are somewhat blurry on our end and we are unable to zoom in on them to clearly see black tips, however the leaf chewing is probably nothing to be overly concerned about. There are many leaf chew insects that are present this time of year and most are native, so native insects on a native tree is good! Leaf cutter bees, many beetle species, various caterpillars etc. If you feel like the damage is too harmful to the young tree, you could go out with a flashlight at night and pick off any culprits you may find.
Watering every day is most likely too much for the tree. You can read our watering guide for trees and shrubs, but if you use a drip hose and run it about once a week (or twice if its been really hot and no rain) and let it thoroughly soak the entire area allowing the water to percolate through to the deep roots, that would be sufficient. If the soil can't dry out in between watering times, the plant can become susceptible to root rot disease. You can feel the soil down to about 3-4 inches and see if it is still wet, and if so give it a few more days to dry out a little more before watering again.
If you wanted to send in additional photos of the black spots on the leaves, that could help to see if its any common issues. You can try to send them in PDF file format and that may allow up to zoom in to clearly see.
Emily
We received JPG-format images, so perhaps those sent via PDF did not transmit for some reason. In either case, we are starting to see leaf damage on a variety of plants from night-feeding beetles like Asiatic Garden Beetle and their kin (cousins of Japanese Beetles). Other insect leaf-chewers include katydids, crickets (there are some "tree crickets" that don't live on the ground like field crickets do), grasshoppers (less common in trees, though), earwigs, leafcutter bees (they carve-out semi-circles in the leaf edges for bundling-up their eggs and are fond of redbuds), caterpillars, sawflies, and plenty of beetle species. Fortunately, even though their chewing can create a bit of an eyesore, these are not serious pests and do not warrant intervention with an insecticide.
As long as the redbud's roots remain healthy and its trunk undamaged, the minor loss of some foliage to damage is inconsequential, especially the later we get in the growing season. If deer happen to visit the yard, protect the trunk from antler rubbing by bucks in the autumn with a cage around the trunk or some other protective barrier that doesn't smother the bark. Deer can eat redbud foliage too, but only while they can reach it.
Minor infections can also cause leaf puckering and brown dead spots (many of which are just collectively called "leaf spots") but these too are not serious and just a cosmetic nuisance. In years with wet or very dew-y weather the fungi or bacteria might spread more prolifically, but you can rake-up fallen leaves in autumn (of if they fall before then) to reduce the presence of spores in the vicinity. This is not a foolproof way to prevent infection in future years, but plant diseases tend to be very weather-dependent in their spread and severity, so an outbreak one year won't necessarily repeat itself to the same extent the next. Redbuds are not super disease-prone plants with regards to leaf spots; the more serious infections occur in roots that are stressed or damaged, or in branch wood that is similarly stressed or injured.
Lilacs can develop wood-boring insect (a moth caterpillar in this case) infestations as they age unless regularly pruned to discourage the moth's interest, and they are also vulnerable to several leaf infections, though different than those that might be present on a redbud. They also struggle over the long term in our summer heat, preferring cooler conditions, so many garden lilacs in our region decline after several years. In this case the lilac's struggles are unrelated to anything the redbud will experience unless the soil drainage in this location was poor, which both plants will not tolerate well.
You can keep an eye on it for now, monitoring it for watering needs before each soaking so it isn't watered too often, and feel free to send us more photos of symptoms if they worsen or change. Leaves can't heal from damage so any existing symptoms won't disappear, even if the cause of them is resolved, but you can look for indications younger growth is developing damage.
Miri
We do not recommend any home remedies as there are a number of risks (in addition to the fact that many just won't work well) to plant health and using such a mixture could easily do more harm than good. Penn State Extension has a thorough page discussing why home remedies in general are not a good idea as pesticide alternatives. (Granted, some of those scenarios they describe don't apply to every use of a home pest-treatment concoction, but they still make valid points. The take-home message is that plant damage is easier to do with these untested ingredients and arbitrary dosages, and impacts on the environment of those household ingredients used in this way could be detrimental.)
The dark blotch on the leaf tip is either abiotic (caused by environmental stressors and not pests or disease) or an unconcerning leaf spot disease or potentially anthracnose. (As an example, many mature sycamore trees in the area were hit with anthracnose outbreaks this spring and they have since shed affected leaves and recovered well with lots of new canopy growth.) Fungicides, even a labeled pesticide product, will not cure existing infection. At best, they help prevent new infections, but not all pathogens keep re-infecting their host plant all throughout the summer. Even those that do aren't always treatable with a fungicide, and such treatments tend to require multiple sprays that might expose beneficial insects to the pesticide (even though that pesticide doesn't target insects, it can still affect bees and other species). These are the reasons why we generally don't recommend fungicides for leaf spot issues; they either risk not working well, could be more trouble an expense then they are worth (since trees don't suffer long-term health setbacks), or are applied too late because once symptoms manifest little control can be achieved.
If any leaves are being totally consumed -- that is, missing entirely or quite torn-off and mostly-missing -- then we suspect deer are responsible as redbud is not unpalatable to them. In that case, a repellent spray might help discourage them (reapply as the label states, which is often after heavy rains) or a physical barrier like a cage/fencing that is removed as the trees mature enough to be out of reach. The only other pest that might defoliate redbud branches would be a communal-feeding caterpillar (Fall Webworm, for instance) but they are fairly unmistakable as they create prominent webbed-together leaf shelters that we don't see here. Sometimes a minor infection weakens leaf tissue (since it creates a dead zone of cells that dry out as the die), and then this brittle area is more prone to tearing during wind or storms, so the leaves get a tattered look as we get later into summer. This is fairly common but should be less prominent as trees mature and have a bigger ratio of intact-to-damaged foliage.
Miri