Strange problem with American holly

I have a beautiful 30 foot american holly in my front yard. Over the past few years I have noticed that while the tree puts out a full crop of berries every year only about half of them ripen to red. The rest remain green. I'm thinking that this is due to a nutritional deficiency in the soil. Has anyone experienced a similar problem?? My garden center guy is stumped.
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American Holly is wide-ranging in vigor and fruit-set from plant to plant, especially non-selected wild trees from seed. It's possible you're not getting very good pollination, or that the individual tree just isn't very vigorous in fruit setting. Perhaps you could plant a male quite nearby and see if that helps. Ilex opaca thrive in MAWD (moist, acidic, well-draining) soils in dappled sunshine. Laying down an acidifying fertilizer like Hollytone, as well as supplementing water during fruit set can also help.
Dave

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Bill/ David: I am wondering if the green fruits are full sized, or aborted? pH is often a culprit, true, but I have seen the most dramatic fruit set in opaca in full blasting sunshine in amenity settings, even though in nature the tree is well adapted to partial shade.
So...are the green fruits the same size as the red fruits? Is the opaca a cultivar to the best of your knowledge? Where on the globe are you? Are there native opaca in your area? Has the soil been tested for pH, etc??
--
Mike LaMana, MS, CTE
Consulting Forester & Arborist
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Mike LaMana wrote:

The fruit in years past was ripe over the entire tree. This year's fruit was fully developed though not fully ripened. None of the fruit is stunted. Incidentally, the tree is in full sun and judging by its height and girth is in good health. I am located in SE PA. The soils in this part of the state are a rich loam. The lawn runs under the tree and I am wondering if the tree is taking in a lot of nitrogen in the lawn fertilizer for leaf growth and not enough potassium for fruit production.
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The N-enrichment hypothesis seems reasonable enough, but I am wondering if there has been another trigger (or lack thereof) that is causing the delay of red pigmentation in the fruits of this tree. I have seen this delay in Ilex opaca before, but have never understood the mechanism. Based on your location and description, I doubt that pH of native soils are the issue here. I know that there are native opaca in the forests of your area (I have seen them often). What are these trees doing vis-a-vis fruit maturation this year?? ML
--
Mike LaMana, MS, CTE
Consulting Forester & Arborist
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