I have a common Lonicera periclymenum, honeysuckle, which has had a problem with yellowing leaves, which eventually drop, for years. Its roots are in the shade, and it receives lots of west sun in the afternoon. I first thought it might be powdery mildew, but no powder rubs off the leaves. It is also near an area where I had to pull out raspberries because of phytophthora root rot many years ago. I fertilized it recently, and try to make sure it has lots of water, but not enough to cause root rot. Has anyone else had this problem, or can anyone suggest a diagnosis? It always starts off strong in the spring, but then deteriorates. It also has a small hebe planted too close to its roots.
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We’ve forwarded your question to the Vancouver Island Master Gardeners, Evelyn. We should hear back shortly.
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Many thanks to Milner Gardens & Woodland’s Gardening Advice line (a partnership between Vancouver Island University’s Milner Gardens & Woodland and the Vancouver Island Master Gardeners Association) for the following response:
It is difficult to tell from the photo which species of Honeysuckle this is but it looks like a deciduous climbing Honeysuckle.
It would be useful to know the following:
The type of Honeysuckle this is.
Where it is planted - in sun, shade? What kind of soil - dry, moist, wet?
When did you notice the yellowing - did it happen all at once or was it gradual over time?
Are all the leaves affected or does it seem to be the older leaves or the newer leaves?
Honeysuckles can grow in most soil types but prefer a moist well draining soil with their roots shaded and growing in full or part sun.
Yellowing and falling leaves can mean a nutrient deficiency, usually nitrogen, or a watering problem. Nitrogen deficiency will usually show up as older leaves yellowing when the plant is actively growing new leaves. The plant is essentially stealing nitrogen from the older leaves to fuel the growth of the new ones. Often over watering and lack of water show the same symptoms.
If this has happened after a long period of dry weather it may just need a good watering. Mulching the base of the plant can also help retain moisture during dry spells. If the plant is in an area that does not drain well letting the soil dry between watering can help.
If the watering is not an issue it could be a nutrient deficiency try giving it a seaweed fertilizer or balanced organic plant food.
Honeysuckle leaf blight also starts with a yellowing of the leaves in the spring on new leaves. The yellow turns to brown and the lower surface of the leaf can show a silvery white color. The leaves are often rolled or twisted and drop. If this is what you observe reducing the foliage density and avoiding watering the leaves and stems when irrigating it will help. The fungus will overwinter on dead leaves so cleaning those up and disposing of them should help.
Aline and Ruth
Resources:
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Thank you Aline and Ruth for your thoughtful reply. Yes, there could be several causes for the leaves yellowing. This is a common honeysuckle which grows wild in England (lonicera periclymenum), so shouldn’t be too fussy about conditions. I think air circulation could be a factor. It is the lower leaves that yellow first, and I suppose those are older. I have fertilized it, so will see if that makes any difference. I couldn’t see any silver tinge to the underside of the leaves. Will thin out the undergrowth and see if that helps.
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