Diseased / poor new growth on garden plants

Question

New growth and buds on a number of my plants is coming through as if scorched, and what little leaf / stalk does come through is rather bobbly and look almost like it's been eaten away, as typically only veins are left.

This has started to happen the last couple of months, and has affected Clematis (severe), Mock Orange, a couple of Roses and Echinops (sea holly, about to flower on the same stems above the damage).

With the exception of the Echinops and one rose, they are 4 feet or taller, and it's as if the problem has started since they've reached a certain height and are taller than the fence. In fact, the lower leaves of these plants are unaffected, leading me to believe that it can't be snails / slugs doing this. Haven't seen any insects or aphids. The whole plant is up against some trellis (6 feet) which is attached to the fence (3 feet).

Any suggestions what this might be and what I can do?

It's ruining these plants, which had been doing very well earlier in the season, especially the Clematis (Will Goodwin). The vast majority of my other plants are perfectly OK.

Thanks for reading.

Answer 1

Diseases and Pests

One of the greatest attributes of clematis is the mass of blooms on such a delicate looking frame. This can at times also be its downfall. If the plant is not securely attached to its host, the stems can be damaged. The resulting wounds provide a target for a wide range of fungi to attack. The plant then severely wilts or collapses. This malady happens most often when the plant is young. "Clematis wilt" is the catch phrase that has developed to describe this occurrence.

Ascochyta clematidina is the most common fungus to attack clematis but it is not always the culprit. Clematis wilt can occur at any time, however it usually happens just as the flower buds begin to open. The whole plant can be affected or as most often happens, only one or two of the stems collapse. If clematis wilt occurs, it is important to remove and destroy the affected stems. The fungus will remain in the healthy looking part of the stem, so it's also imperative that about one inch(2.5 cm) of the stem below the infection be removed. New shoots will soon appear at or below the soil line. At worst this therapeutic pruning will delay your flower display. Its very seldom that clematis wilt destroys a whole plant. If the problem persists the use of the fungicide benomyl will help.

An interesting aside to clematis wilt is that it very seldom affects the species. Also hybrids that have resulted from viticella crosses such as Madame Julia Correvon and Etoile Violette have proved to be very resistant to the various fungi that cause this problem.

Another fungus that might affect your clematis is mildew. It is seldom a problem until late in the season and not a problem at all if there is good air circulation. If mildew is noticed in its early stages it can be easily controlled by many different fungicides readily available. Your local garden center or nursery will be happy to make an appropriate recommendation here.

Earwigs and slugs are the most common pest problems clematis have. Slugs are the most troublesome. As they will always be with us, it's a matter of control not elimination. Slugs prefer to attack young shoots, thus slug bait early in the spring gives the best results. Earwigs usually attack in mid summer and can turn the bloom of a late flowering clematis into a lace work over night. There are many good pesticides and traps available to control earwigs.

Answer 2

Sounds like capsid bug which eats new growth and leaves the newly emerged leaves full of small holes an looking deformed. This includes many outdoor ornamental plants including Caryopteris, Chrysanthemum, Clematis, Dahlia, Forsythia, Fuchsia, Hydrangea, Magnolia, Phygelius, roses and Salvia.

Signs of damage appear from late May to September. The leaves near the shoot tips have many small, brown-edged holes. Affected flower buds, particularly those of fuchsia, may fail to develop, or open unevenly in the case of chrysanthemum, dahlia and other daisy-like flowers.

Capsid bugs suck sap mainly from the shoot tips and buds of many plants. As they feed they secrete a toxic saliva into the plants which kills cells immediately around the feeding area. When the leaves expand from the buds, the dead areas tear into many small holes.

Inspect the shoot tips of susceptible plants from mid-May onwards. If capsids bugs or signs of damage are seen, spray with bifenthrin (Bayer Sprayday Greenfly Killer Plus, Doff All-In-One Garden Pest Killer, Bayer Bug-Free or Scotts Bug Clear Gun).