Would a 40' tall ash tree suffer much from a couple of steel screws driven into the trunk? I am hanging a galvanized farm gate at the end of the drive and need about a 4” square post for the non-hinge side to rest on when closed.

I have several camellias and, on the new leaf growth, the leaves are furled and littered with a mass of tiny black insects. Could you please advise me what to do to rescue my lovely plants?

D Breadner, e-mail.

The problem you have with your camellias sounds like black fly (aphids) which are sap-feeding insects, ranging in size from 1-7mm long, which infest plants, especially on the shoot tips, flowerbuds and the underside of younger leaves. The foliage may be sticky due to the sugary honeydew that aphids excrete. A black sooty mould often develops on the honeydew.

White cast aphid skins often accumulate on the upper leaf surface or soil beneath where the aphids are feeding. Aphid damage can result in stunted growth with curled or distorted leaves.

Aphids are also known as greenfly and blackfly, but other types may be yellow, pink, white or mottled. For much of the year, some aphid colonies consist of wingless females that give birth to live young. Winged forms develop when overcrowding or a deterioration in the host plant induces a need to move to another plant. Some aphids can transmit plant virus diseases when they move from one plant to another.

Aphids have many natural enemies, including ladybirds, hoverfly larvae, lacewing larvae and several parasitic wasps. Unfortunately, damaging aphid infestations often build up on garden plants before the natural enemies are active in sufficient numbers to achieve control.

Pesticides generally give a higher level of control. Bifenthrin (Scotts Bug Clear, Doff All in One Garden Pest Killer, Bayer Sprayday Greenfly Killer Plus) is a contact insecticide that can be used on ornamental plants. Check the product instructions as there are restrictions on how many applications can be made.

Imidacloprid (Bayer Provado Ultimate Bug Killer) is a systemic insecticide that is absorbed into plant tissues and is taken in by aphids as they feed. This means that aphids feeding in curled leaves can be controlled. Another systemic insecticide, thiacloprid (Bayer Provado Ultimate Bug Killer Ready to Use) can be used on ornamental plants. Read the manufacturer's instructions regarding restrictions on the use of this product and harvest intervals. Even with systemic insecticides, it is only feasible to control aphids on plants that are small enough to be sprayed thoroughly. Aphid infestations on tall trees have to be tolerated.

I have a peach tree and some bug keeps getting the fruit before it is ripe. What can I do to stop this happening again this year? If I pick some before they are ripe what is the best way to try to ripen them?

Meg, Norwich.

Squirrels are a common problem for peach trees as they eat shoot tips, flowerbuds and will eat the fruit - they are generally very destructive. They will even pull off plant labels and use them to sharpen their teeth! The best way to control them is either to shoot them, which is not always possible in a built-up area, or to trap them in purpose-built traps. Both these methods of control are not particularly good for the domestic garden and, as squirrels are very mobile, another one will soon move in to fill the space left by the last. The best way to save your peaches is to use some netting to protect the fruits during the times when the squirrels start to take an interest in them. Permanent wire mesh fruit cages are best as squirrels will chew through plastic ones.

Peaches are variable in their fruiting, but in favourable conditions a peach or nectarine bush may yield an average of 13.5 to 27kg. Harvest the peaches when they are ripe or almost ripe. To test for ripeness, cup the fruit in one hand and gently press near the stalk with the fingertips. If the flesh is soft, it is ready to harvest and should be easily parted from the tree. Place the fruits in containers lined with soft material and ensure they are not touching each other. Some may need a day or two to fully ripen.

I was lucky enough to win a lovely cyclamen in a raffle at Christmas. I have kept it well and it is throwing out seed pods which I have put in little paper bags and secured to collect the seed. Could you please tell me when and how to plant them?

The leaves of the plant have gone silvery although it looks healthy. Will this affect the plant?

V Allen, e-mail.

Among enthusiasts there is much discussion about the most efficient ways of germinating cyclamen seed in order to obtain the most consistent and highest percentage of germination. For consistent germination, fresh seed is needed and in some species, it is essential. It should be sown as soon as it is ripe - ideally being gathered just before the capsule splits open - when the seed has coloured to a light brown.

Soaking seed in warm water (with a wetting agent, such as a drip of washing-up liquid) for about 24 hours before to sowing is beneficial.

Light acts as a germination inhibitor to cyclamen so ensure the seeds are correctly covered. If seed is allowed to dry out after germination has started, this is likely to be fatal as in Mediterranean plants, which grow in autumn-winter-spring, germination takes place generally in cool conditions - 13 to 15C is ideal.

Since it is recommended that seedling tubers should remain in the same container until they go dormant in their second growing season, it is better to sow in pots rather than in seed trays or flats, so that there is adequate depth. For larger quantities, the blue/black plastic, 15cm deep boxes used for packing mushrooms, are ideal.

The compost used should be similar to that for potting cyclamen tubers, but with a reduced level of fertiliser. It should be free-draining but moisture retentive - which indicated a significant proportion of grit, plus some organic matter.

The seed should be sown on the surface of the compost, spaced about 2cm apart, and covered with a layer of grit 5-7mm deep.

In general, autumn-flowering species will germinate in autumn, and spring-flowering species in spring. However, if no seedlings are seen within the first 12 months, the pot should not be discarded as seedlings can appear two or three years later, especially when the seed has been subjected to dry storage or is old.

Send your questions to Martyn Davey, Easton College, Easton, Norwich NR9 5DX or you can e-mail him at Martyn.Davey@easton-college.ac.uk

Martyn has been sent several questions so please be patient if your reply does not appear immediately.