For three years, my plum tree has had leaves that curl and shrivel somewhat. I have heard of aphids causing leaf
curl in plums, but I don’t see many aphids.
I also have a peach tree that has “Peach Leaf Curl” or Taphrina
deformans and the symptoms on the plum leaves look similar to that.
Here is what I wonder:
- The peach and plum are at least 100 yards apart. Is it really possible that the peach infected the plum?
- With the peach tree the fruits are also affected but with the plum
fruits do not appear to be affected. - Are peach and plum affected by the same diseases?
Both peach and plum trees are in the genus Prunus. Your plum tree’s problem sounds like plum pockets and peach leaf curl, which are caused
by fungus (usually Taphrina).
From Iowa State University Plant Pathology:
Have you noticed lately that your peach leaves appear curled or puckered?
Do leaves appear to be lighter than normal, flushed with red, blistered,
distorted, and curled? Chances are your tree has peach leaf curl, a
fungal disease caused by Taphrina deformans. Although peach leaf curl is
primarily a disease of peach, nectarines are also affected. Peach leaf
curl is first noticed in spring when young leaves start to emerge. The
entire leaf or a portion of it may appear crinkled and curled with
flushes of red or purple . Later on in the season, the fungus begins to
produce spores and leaves appear silvery or powdery gray. Infected leaves
turn yellow and brown and fall off the tree and are replaced by a new set
of foliage. Flowers, young fruits and stems may also be infected.
Affected fruits are distorted with wrinkled, discolored areas on the
surface. Extensive defoliation may affect fruit yield the following year
and may also predispose the tree to winter injury and other diseases.
Plum pocket is a disease in plums caused by Taphrina communis. Leaf
symptoms are similar with peach leaf curl and the plums appear to be
distorted, wrinkled, and puffy. This disease is not considered a serious
problem in most commercially cultivated plum varieties.
Here is Oregon State University’s online guide to plant diseases (aimed at professional gardeners) This is Washington State University’s site intended for home gardeners.
I don’t know if your plum could have gotten the same species of Taphrina fungus
that is affecting your peach (i.e., Taphrina deformans), but the conditions in our climate are probably ideal for this type of fungal disease.
University of California, Davis says that the pathogen which causes peach
leaf curl survives on tree surfaces and buds, and is enhanced by wet
spring weather.
From University of Nebraska Plant Pathology:
Plum Pockets is very similar to the well-known disease peach leaf curl.
It reached epidemic proportions on plum in the 1880’s and sand cherry in
the 1940’s. The disease is still common today but rarely has an economic
impact on stone fruit production. However, its unique symptoms always
seem to peak the interest of individuals who are seeing it for the first
time. The disease is caused by two species of Taphrina. Taphrina communis
(Sadelbeck) Giesenh. has a worldwide distribution. Its hosts include plum
(Prunus angustifolia) and several wild Prunus spp. found in America.
Taphrina pruni primarily infects European plums and is rarely found in
America. The disease cycle of Taphrina communis is similar to that of
Taphrina deformans (peach leaf curl). The fungus overwinters as conidia
on twigs and bud scales. Infection generally begins at bud break when
these spores are rain splashed to susceptible green tissue. Leaves,
shoots, and fruit are all susceptible but symptom development is most
common on fruit. The fungus invades host tissue directly through
epidermal cells. Once the fungus is established, a specialized mat of
fungal cells (hymeneal layer) containing asci and ascospores forms. The
asci are not protected by a specialized ascocarp. Ascospores are
released, germinate and begin budding, much as a yeast does. Conidia (bud
conidia) serve as secondary inoculum in the spread of the disease.
Initiation of the disease cycle is favored by cool wet weather.
You might consider bringing in samples of the affected leaves to a Master
Gardener Clinic for a definitive diagnosis. They may also have more information on whether the disease can pass from peach to plum, or whether your two types of trees simply have two different strains of the pathogen.