We asked you what pest, disease and plant problems you’d like Alan Titchmarsh’s advice on. Hundreds of you responded with questions about a host of problems on a wide range of flowers, fruit and veg.
Here, exclusively for subscribers, Alan Titchmarsh offers organic solutions to a selection of your plant disease questions. Come back here, next month to find out whether he’s answered your question.
Vine weevils are destroying my plants. What is the best way to get rid of them and is there any way to prevent them? Gary Lindsay
Alan Titchmarsh says:
Vine weevil is a heartbreaking pest to encounter, not least because the damage often goes unnoticed until the plant collapses due to the roots being eaten away. Always use fresh and sterile compost when potting up plants, as well as clean containers. Water susceptible plants with a biological nematode vine weevil control such as Nemasys, strictly in accordance with the instructions on the product.
Some of the leaves on my containerised apple tree are coated in white stuff then curling up and dying. What’s wrong with it? Deb
Alan Titchmarsh says:
Your potted apple tree is suffering from mildew – a fungus disease that is especially prevalent when trees are under stress, which usually means they are dry at the roots. Make sure that there is plenty of air circulating around the plant (thinning out overcrowded stems will help) and try to keep the compost gently moist at all times. Apply dilute liquid tomato feed once a week between April and September to build up the plant’s ability to grow through the attack.
I have a severe infestation of box caterpillar. Should I pull it all up? Roland Backhouse
Alan Titchmarsh says:
Don’t get rid of your plants just yet! Well fed and watered they will eventually recover provided you take other precautions such as hanging up a box moth trap and spraying three times during the growing season (when each of the three generations of box caterpillars emerges) with a solution such as Top Buxus Xen Tari. Spraying the bushes with a sharp jet of water will also help them to shed the caterpillars which will be eaten by birds.
There is a white froth on some of our plants, is this harmful? Amanda
Alan Titchmarsh says
This is ‘cuckoo spit’, and each collection of froth will be protecting a single frog hopper insect. They do little damage to plants but the spit is unsightly. Squirt them with a sharp jet of water from a hosepipe to remove them.
I have had no gooseberry sawfly for years. This year, I covered my gooseberries with netting to keep off birds, but a week later, all the leaves had gone and there were caterpillars all over the bush. What should I do? Bob Sparkes
Alan Titchmarsh says:
The birds might well have been helping by eating the gooseberry sawfly! It will be worth uncovering the plants. If there are too many caterpillars to hand pick, try spraying with the biological nematode caterpillar control Nemasys in May, when attacks are usually first noticed.
Can you suggest any chemical-free solutions to black spot, rust and other fungal disease problems in roses? Samantha Merridale
Alan Titchmarsh says:
Roses almost always succumb to these diseases when they are under stress and that usually means they are dry at the roots. So…make sure that the soil in which they grow is moisture retentive. Clay soils are traditionally enjoyed by roses for that reason. Beef up lighter soils with plenty of organic matter – well-rotted compost and manure – which will help hold on to moisture. In prolonged dry spells, soak the soil – especially around newly planted roses – using a hosepipe. Varieties with delicate foliage are particularly susceptible, so choose roses with thick, leathery leaves – along with varieties of the rough-leafed Rosa rugosa – and you will find they are much more likely to resist these diseases.
Why are the leaves on my potted camellia turning brown? Karen Johnstone
Alan Titchmarsh says:
This is most frequently caused by scorching sunshine, though there are also fungus diseases that cause leaf browning. In every case, pick off the affected leaves and dispose of them. ‘Sun scald’ is caused when the leaves are subjected to overly strong sunshine – camellias grow best in dappled shade. They also need lime-free ‘ericaceous’ compost when being grown in a container, but alkaline soil conditions cause yellowing rather than browning of the leaves. Dryness at the roots is another cause of leaf browning. In short, make sure your container-grown plant is shaded from bright sunshine and that the compost is never allowed to dry out completely.
My Viburnun tinus has branches that suddenly turn brown and die. Why? Jemima Cole
Alan Titchmarsh says:
This is a common problem and there are several possible causes. Some form of mechanical damage may be responsible – a cut to the stem, damage by a pest or some such physical occurrence. The simplest thing to do is to snip out the affected stem, well back into healthy tissue. Viburnum tinus is a vigorous plant and will soon recover from the attack. One or two fungus diseases may also be responsible. Good drainage at the roots and good air circulation around the plants will help to prevent attacks. In every case, cut out and dispose of infected tissue. The plants also benefit from an occasional feed with blood, bone and fishmeal.
How should I deal with peach leaf curl? Gill Hollick
Alan Titchmarsh says:
Peaches in a greenhouse are seldom affected but those outdoors are likely to succumb every year. You will find that if you rig up a sheet of polythene above wall-trained trees in January, to act like a curtain, attacks will be much reduced. Remove any leaves that are affected and dispose of them – do not put them on the compost heap where the fungal spores can survive. Spray the unfurling leaves with an organic foliar feed every couple of weeks, which will improve the plant’s overall strength. As you have noticed, as the season progresses the leaves cease to be attacked.
My broad beans were riddled with chocolate spot and blackfly. How can I prevent this? Marion Hayman
Alan Titchmarsh says:
Broad beans are frequently attacked by a fungus disease called chocolate spot. It is prevalent in damp weather and where plants are growing too close together which results in poor air circulation. Make sure the site you choose is in full sun and that the plants have room to grow without touching one another – space them about 30cm apart. Don’t compost any affected plants, don’t save seed from affected plants, and change the place in which you grow your broad beans each year. Blackfly (aphids) love the tender tips of broad beans, so once the plants are 45-50cm high, pinch out the shoot tips to allow the plants to concentrate on developing their beans and to remove the tender tissue.
from BBC Gardeners World Magazine https://ift.tt/yahEtGU
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