Ilex Oakleaf

Question: We had three Ilex Oakleafs planted in the fall of 2022 and this spring two of them have developed strange coloring, dropped many leaves and we are concerned they may have some kind of disease. Are you able to tell from these photos what the issue is?

responder: Answered by theHome and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied May 10, 2023, 1:38 PM EDT
response: We see and share your concerns but don't think that the issue is related to a disease pathogen or insect pest.  This looks more like environmental stressors, which can include weather, and problems with planting or the site itself, causing a failure to establish well.  While hollies can shed some older leaves (which yellow first) each spring, this is an unusual amount of leaf drop and browning down below. ( the brown balls are blasted flower buds).  Ideally, broadleaved evergreens like hollies are planted in the spring, so they have a cool, moist period and all the time of summer to establish roots. Were they monitored and watered when needed throughout the fall, right up until the ground froze for winter? (2023 was a pretty dry year overall)  That said, yellowing leaves can indicate not only a lack of water, but also sometimes too much water.  We can see the downspout in the background... does it deposit water on the two that are struggling?  Here is our page on planting:  https://extension.umd.edu/resource/planting-tree-or-shrub  Were they pot-bound and were the roots well-loosened upon planting?  Could they be planted too deeply? It sounds like you were not the one installing, but it is worth reading through for clues.   Are they under warranty? Would they extend it? It is difficult to say if they'll recover given how drastic the leaf drop is, but there's nothing that can be done except to just keep monitoring them for watering needs.  This page will tell you how to best water them when needed, including how to make sure the water is getting where you think it is:  https://extension.umd.edu/resource/watering-trees-and-shrub  One final thought. Any chance any weed killers were applied nearby or over the root system of the plant?   Christine

responder: The Question Asker Replied May 10, 2023, 3:57 PM EDT
response: Thank you Christine, much appreciated! We did have them planted by a landscaper and thought they were watered appropriately but given your recommendation we will water a bit more intensively over the next few weeks. The downspout you astutely noticed in the picture is buried underground and doesn’t empty in the area of the Hollys so don’t think it’s too much water that is the issue. The landscaper who planted them suggested more water and some fertilizer would be needed so I wanted to double check that recommendation with you!I’ve included a picture of the three Hollys next to each other, the Holly on the right seems more deeply green than the other two, which I thought was odd and suggested there might be a unique issue for two of them. But, sounds like that is unlikely. Thanks again for your information!SamOn Wed, May 10, 2023 at 1:38 PM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied May 11, 2023, 4:31 PM EDT
response: Hello Sam,  As a very rough guideline and example, watering during a hot dry spell might need to occur about once a week if the soil drainage is good and the plants not highly drought-tolerant. (Hollies are not.) It's not uncommon for our autumn weather to produce below-average rainfall and mild drought conditions, and new plantings are more sensitive to getting too dry during establishment than more mature plantings. The raised-bed (more-or-less) nature of this planting site suggests it might have above-average drainage, which is a boost to help avoid waterlogging roots but may mean it dries out more rapidly than the surrounding at-grade (and potentially more clay-laden) soil.  The best way to judge watering needs, though, is to literally just stick a finger in the ground to feel the moisture levels (perhaps aided by a trowel or screwdriver, given the depth required). If damp to the touch at six inches down, the plants can probably wait for watering; if becoming somewhat dry to the touch at that depth, a thorough watering would probably benefit them. This applies mainly to plants whose roots were well-loosened upon planting, though, so in cases where this might not have occurred, it can be harder to judge when watering is needed since the soil type inside the root ball core is very different and less moisture-retentive than the surrounding earth, making it easier to accidentally over- or under-water plants. In such cases you'd need to try probing the root ball itself (harder to do if the roots are dense) to judge how damp or dry it's becoming.  Over-watering is just as harmful to plants as under-watering, if not more so, because in the former opportunistic fungi or fungus-like pathogens take advantage of stressed roots and cause dieback, worsening the problem. Under-watering can share nearly identical symptoms with over-watering, but the leaf loss caused by under-watering can be remedied over time by replacement growth if the plant is relieved of its stress and slowly recovers. There is no curative treatment for overwatered roots, which is why it's best to always make sure watering is needed before making assumptions or watering on a set schedule without checking the soil beforehand. The landscaper's suggestion is not outright wrong -- it very well could be drought stress manifesting now -- but they can't know that without doing some monitoring.  The rightmost holly with more even-green foliage looks more normal to us than the one in the center; plus, it's dropping way fewer leaves, and its fallen leaves are brown, which are expected during a typical springtime holly leaf shed of a few of its older, lower leaves. The loss of fresher leaves on the center plant is definitely concerning and is not normal. Often, such symptoms suggest a problem with root health. This aligns with the fact that the flower buds blasted (died, turned brown before opening) as they form months ahead of actually opening but must retain a supply of moisture (just as leaves do) in order to stay alive while dormant and in order to open fully. Plants under stress do tend to abort flowers or fruit at any stage of their development if they're present during that period of stress.  Fertilization can sometimes help remedy yellowing IF the roots are in good shape and the soil is low on certain nutrients, but that is almost certainly not the case here. Don't fertilize stressed plants as this can only worsen the situation; at the very least, ailing roots won't be able to absorb the nutrients no matter how abundant they are in the soil. Laboratory soil testing is the only reliable way to know what the current soil nutrient profile is (serious deficiencies are uncommon) and how acidic or not (the pH) the soil is as it pertains to the preferences of certain plants. Improper pH will impact how easily roots can access the nutrients they need, and while a mismatch can result in yellowing, that similarly does not appear to be the case here, especially considering the leaf shed and the fact that the yellowing appears to be impact young and old leaves alike, not just one group over the other as would be expected of a deficiency.  Miri