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Q. We have a Privet Hedge, approx 7 ft by 2-3 ft. Unsure of it's age. Early spring after the spring growth had appeared, 2 plants curled up & died. They had lost most of their leaves the previous autumn, however when they sprouted in the spring we thought all was OK. We had cleared all the ivy from around the base of the plants the year B4 & thought maybe this had had some effect. Now it seems that part of 2 other hedges are also starting 2 die. They are not anywhere near the 2 plants that died in the spring. Somebody suggested it was because of a lack of water over the summer, however one of the hedges is situated behind our herb garden and so was watered regularly during the summer. The leaves now are a mix of dark purple / red and yellow / brown. Some of the plants show some new green growth, others don't. They appear to have thinned out quite considerably too as we can now see through to the other side. Some of the old wood has a green soft coating to it, like a thin moss. Also a few months back I noticed some of the leaves had curled up on themselves and turned black, with further investigation I found a small cream colored larva (3mm) inside the leaf walls surrounded by what seemed to be digested black remains of the inside of the leaf. I have not been able to find help anywhere on what this might be. It doesn't leave tunnels like a leaf miner, rather it just seems to eat everything in between the 2 walls. Please I don't know what to do next. I feel we are in danger of losing all the hedge. It was last pruned late spring / early summer and we've been afraid to touch it since then. I have noticed a few other hedges in the district looking somewhat the same, but there are others which look fantastic. Is it worth putting down some Sequestered Iron or spraying with a fungicide? A. I think the leaf miners you found are incidental rather than the cause of the problem, they are not uncommon on privet. It sounds like either honey fungus or wilt (a wonderfully vague term), both are fungal diseases that will readily attack privet and cause the symptoms you describe and over the time scale you describe. If it is honey fungus, you should be able to find some of the bracket-like fruiting bodies on the trunks of the plants. Wilt is caused by one of a group of fungi that give no outward signs other than the symptoms of the plant that is suffering. In either case there is little you can really do directly. Cut out all of the dead wood and stems and burn them, clean pruning tools carefully afterwards so not to spread spores. Clear under the plants of weeds, ivy, dead leaves and any other debris and give the hedge a top-dressing of fish blood and bone meal lightly forked in to help build up the strength. I have to say though that the outlook is not very positive, particularly as you say other hedges in the area are affected, it seems like the disease is endemic and may re-infect. Try my suggestions, but be aware that you may eventually have to replace the hedge with something that has resistance to the disease that is affecting it.
Q. I have recently shredded some laurel bushes (removed as they were inappropriately planted), and plan to use the resultant mulch on flower beds. I have been advised by a friend that I should not do this as laurels are toxic. Is this correct? A. I've never come across this, though it may have some grain of truth as virtually nothing will grow under laurels (their roots and light shielding abilities help this as well though), many plants have various chemicals in their leaves to deter weeds or competitors. As long as you compost them properly before using as a mulch, you should have no problems. No shredded plant material other than bark should really be used as a direct mulch.
Q. My neighbors Leylandii is now 15ft high and growing about 3 ft a year! I have asked him to cut this down to a reasonable height of about 6ft which he refuses. He actually pulled up trees under a TPO (tree preservation order) 6 years ago and planted these monstrous green things and now the view of the valley is totally ruined. What is the current legislation regarding this and if all else fails how do I kill them? A. Despite promises of legislation, there is still no law about the height of a boundary hedge. Your best approach is probably to go to your local council and ask if there is anything they can do. If trees under a TPO were removed they can be made to be replanted as they were, was anything done at the time? I don't know how it would be considered so long after the event. What you can do is to prune the roots where they encroach upon your land, i.e. dig down and cut them at the boundary, if this damages them, then so be it. Obviously though, this is hard work and not the best approach for a conciliatory outcome. As for killing them, this would be against the law, you are not allowed to poison them even where they encroach upon your land.
Q. I planted a hedge of 25 Thuja conifers in late September, 20 inches apart in a well-prepared trench. The trees run in a North-South direction for approx. 40 ft. and there is a 6 ft. fence to the Western side. The trees appeared to be doing fine until about a week ago, during recent heavy rains in the UK. On 5-10 trees there are a number of brown leaves, especially nearer the ground that are falling off. I can accept that there may be some loss over the winter. However, some leaves and stems higher on the plants in random locations are turning an almost blue-black color and falling off. Is this normal, or do I need to take action? Thanks for your question. It's not always easy to work out what's happening when conifers start dying off. I wouldn't expect the browning off or blackening of stems at all, neither are expected responses for newly planted conifers in such a short time. A. I think the strongest possibility is an infestation of Phytophthora fungus. The fungus thrives in damp and waterlogged soils so may be in your soil, but the speed at which your plants have been affected implies that there is a good chance that they arrived with it. It kills the plants from the roots upwards and can give the blue/black color on the stems that you describe. The roots of affected plants are reddish brown or black rather than white. To quote from the MAFF website: Some trees, such as Lawson's cypress are highly susceptible to Phytophthora root rot. Nevertheless, root rot is almost always the result of over-watering, root damage or prior drought stress, poor soil conditions, flooding, etc. Pythium and Phytophthora can almost always be found in dead, rotted roots, so may not be the primary cause. Except for highly susceptible species, re-planting with healthy trees should not be a problem if the soil and environment are improved and good horticultural practices are followed Other possibilities - you'll need to investigate a bit further: 
Conifers have a delayed reaction to stress and damage that is more
immediate in broad-leaved plants. They may have been damaged or dried out
before you got them and then showed signs later. A couple of years ago I
bought 6 "bargain" conifers at an auction that looked very
healthy, took them home and watched them turn brown and die over the next
two weeks. They had been totally dried out in their containers and then
watered just before I bought them.
Cure? obviously depends on the cause. If it's Phytophthora there's nothing you can really do. I'd go back to where you bought the plants from, but there's no chemical control available to cure it. The fungus remains in the soil so despite what MAFF say, I wouldn't risk planting the same again. Tsuga heterophylla (Western hemlock - not keen on exposed windy sites) and the ubiquitous Lleylandii (tough as old boots and grows like mad) are resistant. |
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