Plum: lower leaves turning yellow

What it is likely to be on plum

1. Root rot

   Candidate 1common on this plant

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Plum — growing

   Checked 2026-08-13

   The consequence of prolonged waterlogging rather than an independent event: water moulds that are present in most soil and compost become active when roots are deprived of air, and colonise tissue that is already dying. The treatment is therefore the watering, not the fungus.

   Points towards it

   • · plums are grown on rootstocks that resent standing water at the roots
   • · failing roots yellow the whole tree rather than the oldest leaves alone

   Argues against it

   • · dry ground rules out waterlogging — this rules it out entirely.

   Check this next

   Dig a hole a spade deep beside the tree after rain and see whether it holds water. Plum on heavy ground that lies wet in winter yellows generally and makes short weak growth, and the trouble is under the surface rather than on the leaves — nothing on the foliage will tell you.

   What to do now

   Improve the drainage rather than feeding the tree, and stop watering if it is in a container. On heavy clay the durable answer is a raised planting mound or a different position, because no rootstock in common use tolerates roots that sit wet all winter.

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Plum — soil

   Checked 2026-08-13

2. Normal leaf ageing

   May be normalvery common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Plum — growing

   Checked 2026-08-13

   Not a problem, and included as a candidate because it is one of the commonest explanations for a single yellow leaf on an otherwise healthy plant. Every plant sheds its oldest leaves; a differential that cannot return 'nothing is wrong' will always find something to blame.

   Points towards it

   • · the oldest and most shaded leaves inside the canopy go first
   • · a scattering of leaves rather than the whole tree
   • · nothing has happened and the tree is growing normally at the tips

   Argues against it

   • · a whole tree yellowing at once is not ageing — this rules it out entirely.

   Check this next

   Look at where the yellow leaves are hanging. A few inside the canopy and low down, on a tree whose outer growth is green and extending, is a plum shedding what it can no longer light — and a tree carrying a heavy crop does more of it, because the fruit takes priority over the oldest leaves.

   What to do now

   Nothing, beyond noting whether the tree is congested enough to be shading itself badly. If it is, that is an argument for thinning the crop and for a light summer prune once the crop is off — never a winter one, which is when silver leaf infects.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Plum — pruning

   Checked 2026-08-13

3. Normal autumn leaf fall

   May be normalvery common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Trees and shrubs — seasonal change

   Checked 2026-08-13

   A deciduous tree, shrub or cane turning yellow through autumn before dropping its leaves. The plant is withdrawing nitrogen and magnesium out of the foliage and storing them in wood for next spring, which is precisely why the leaves go yellow — the green is being taken back. Diagnosing it as a deficiency inverts what is happening, and the feed that follows arrives at the one time of year the plant has no use for it.

   Points towards it

   • · senescence runs through the entire canopy at once, because it is triggered by day length rather than by anything local to a branch
   • · nothing was done to the tree, and it grew normally all season — which is evidence FOR a seasonal process rather than against it
   • · it is driven by shortening days and cold nights outdoors
   • · old and new wood colour together rather than one ahead of the other

   Argues against it

   • · one branch or one side yellowing while the rest of the tree stays green is not seasonal — nothing about autumn reaches half a tree — this rules it out entirely.
   • · autumn colour takes the veins with the rest of the leaf, so a green vein network held against yellow tissue means something else is going on underneath it
   • · a tree that was recently moved or planted has a much better explanation available for a general yellowing

   Check this next

   Check the date and then check the hedgerow. A fruit tree colouring evenly from September onwards, at the same time as everything else deciduous around it, is doing what it does every year — the yellow is the tree taking its nitrogen and magnesium back out of the leaves and into the wood, which is why a deficiency is the one thing it is NOT evidence for.

   What to do now

   Do nothing, and specifically do not feed — autumn nitrogen on a woody plant pushes soft growth that will be killed by the first hard frost. If the tree carries scab or leaf spot, rake the fallen leaves up and remove them rather than composting them in place, which is a sanitation job rather than a treatment for the colour.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Feeding trees and shrubs

   Checked 2026-08-13

Narrow it down

This page lists everything at once, which is the right shape for reading and the wrong shape for deciding. The interactive tool asks one question at a time, starting with whichever would separate these causes fastest, and stops as soon as further answers would not help.

Opens with the plant and the symptom already set. Nothing you answer is stored or sent anywhere — the answers live in the address bar and nowhere else.

What this does not cover

These are the causes GrowingHQ holds rules for on plum — not every cause there is. Where several problems look alike, the honest answer is often that they cannot be told apart by eye, and a page that named one would be guessing. If none of the above fits, the general lower leaves turning yellow page lists causes across all plants, and the Plum profile lists the problems it is prone to.