Tree Fruit - Pests and Tips
Problems with fruit have to be the most frustrating problems of all, fruit are the whole point of having a fruit tree and if you can't get any, then there's no point in giving it space in the first place. These are some of the commonest ailments that might affect a fruit tree along with tips to aid your crop.
Q. Why do my pears or plums not do so well while my apples are fine?
A. Pears are not as all round tough and resilient as apples. They don't like exposed positions, shady positions or frost pockets. Early flowering means that the flowers may be damaged by frost and that there are less pollinators around. Pears need another pollinator tree generally and there are usually less pear trees around than apple trees in neighboring gardens, so you need to provide your own. Pears also need more sun and fall warmth to ripen the fruit. A final and possibly important reason is that allowing grass to grow under a pear tree will make conditions more difficult for the tree as pears don't like competition.
Plums are early flowerers in the spring and may be affected by frosts as are pears, but if pears do well locally, you need to look to other reasons. Drupes - fruit with a single large pip or stone - tend to need soil with more nutrients than pomes - fruit with many small pips such as apples and pears. Drupes also need a reasonably limey alkaline soil to do well so a dressing of lime and fertiliser will help them to do better.
Q. Can I grow fruit trees from pips or stones ?
A. Yes you can, but in general I wouldn't bother. If you buy fruit trees, you usually get a grafted named variety on a particular rootstock that pre-determines the tree's size. In other words, you're buying a "pedigree". If you grow from seed you're growing a mongrel, now while mongrels might be great dogs, they're no so great when they're fruit trees.
The most likely thing to happen is that you'll get a large vigorous tree that has so-so fruit, less likely you might get a poor or good tree with an equal chance of either. So you might as well pay not a lot of money over the lifetime of the tree, easily less than a pound a year) to get something that is pre-determinedly well worth having. A seed grown tree generally won't flower for at least 5 years - considerably more than a named grafted variety. If you've the space, time and inclination, it might be fun and you might even equal the luck of retired London brewer Richard Cox, who in 1825 grew a seed from a "Ribston Pippin" into "Cox's Orange Pippin" one of the all time great apples. Some of you however will notice that it happened in 1825 and there's no other similar story from the last 200 years to match it.
The notable exception to this rule of thumb is peaches which will produce trees that produce fruit almost identical to the peach that supplied the stone in the first place.
Q. The ends of many new shoots on my fruit tree are dying back, is this serious?
A. This is a common ailment particularly in late spring to early summer, new shoots in particular die back for the end 4-6" killing a few leaves in the process, the leaves shrivel up turn brown and die. It is a result of fungal infections affecting each shoot individually - i.e. it's not a disease that the tree gets as such, but one that each affected shoot contracts as an individual infection.
You could treat the whole tree for the fungal disease, but usually by the time you've noticed it, it's too late and the damage is done. It is not often serious and the tree shakes it off, the way you shake off a cold. Damaged shoots and leaves can be cut off, or I just leave them a while and then crunch up the dead dry leaves with my hand.
Q. There are loads of strong vertical shoots growing from my tree, is this a problem?
A. This is the usual response of a mature tree to having too much wood removed in one go - to produce a mass of "water shoots". The shoots are best left to reach at least 1-2ft in length and then removed in stages over months at least if not a couple of years, leaving only enough to replace what has been removed. If they are removed too quickly when too small, the tree simply makes a load more.
Q. My tree looks healthy and produces flowers, but never fruits, why might this be?
A. There are two likely reasons for this. If it flowers early in the season and you live in an area with many late frosts, then it could be that the flowers are being damaged and fall before they can be pollinated. It could be that your tree requires another of its type for cross pollination, in which case bring another in.
Q. My trees crop heavily some years, but then produce little or nothing the year after, why is this?
A. Your tree has got into the habit of "biennial bearing". This means that in the first year it puts so much effort into producing a large amount of fruit, that it needs a year off to recover and build its strength back up.
The answer is to thin out the fruit in early-mid summer. The "June drop" happens in late June to early July and is a natural process where the tree loses many superfluous small fruits. Despite this it will often retain far more than we would like it to for consistent fruit production. Once this natural drop of fruits has occurred, you can thin out the fruits even more. A rule of thumb here is to leave one fruit per leaf area the size of your hand, but this is not easy to gauge, especially when the fruits are concentrated in some places and not found at all in others. Remove damaged, crowded, very small, malformed, diseased etc. fruits leaving only the best to develop, you need to be a lot more ruthless than you think, probably at least half of all small fruits can be removed.
Q. How can I prevent birds from eating my fruit?
A. Birds favor some fruits over others, cherries, redcurrants and strawberries are the favorites and as far as birds are concerned, red in general is a color that says "Hey look - dinner!". The most effective way is to net the fruit or erect cages. Draping a net over the tree or bush is not totally effective as many birds will eat those that touch the net.
Providing bird baths or a source of water of some kind near to the fruit can reduce fruit losses, as part of the reason birds eat fruit is for the water as much as for food. Fruit is a poor source of energy for a bird's high metabolism.
Q. My apples, apricots, pears or plums are maggoty, how can I prevent this?
A. In mid to late summer, this is likely to be the caterpillars of codling moths. The caterpillar enters the fruit of apples, pears or apricots (and quinces) while it is very small feeds in the core of the fruit and then exits by the time the fruit is ripe by a hole usually near the blossom end of the fruit. Treatment is by the insecticide bifenthrin in early summer followed by another application about 2 weeks later. The timing of the application can be gauged using pheromone traps to see when the moths are most active. Alternatively if you don't want to apply an insecticide, then pheromone traps can catch enough moths if the trees are reasonably isolated to reduce the number of maggoty apples. You will never really totally control codling moths.
In early to mid summer on apples, this is likely to be apple sawfly. Fruitlets fall off before maturity and have a maggot hole in the side that is surrounded by sawdust like frass (for some reason caterpillar dung has a special name - frass). Sawflies can be a worse problem than others as the caterpillar may leave one fruit and enter another, even up to 3 fruits altogether. Control is by picking and destroying affected fruits before they fall off and the moth escapes. If there have been heavy infestations in the past, then spraying with bifenthrin at the point where the petals fall can be effective.
Plums - this could be due to the plum moth or plum sawfly. Fruits tend to mature prematurely and may fall off the tree. Control is difficult as chemicals against the moth are not generally available except to professional growers, the sawfly tends to occur locally and sporadically. If sawfly has been a problem in previous years, then spraying with rotenone or derris a week or so after the petals have fallen off may help.
In all cases with maggots, the moths or sawfly tend to overwinter in the soil under the trees. A simple way of tackling the problem is to apply a thick mulch of organic material under the trees at least 2 feet radius from the trunk and preferably more - to 6 or 8 feet even for larger trees. This mulch will help the trees by conserving moisture, adding organic matter to the soil and it will give the moths / maggots somewhere to burrow. So how does this help? Mulches are loose and so in the late fall and winter, rake over the mulch and spread it, scatter some bread or other bird attractor and in will come the local wildlife to help your pest problem. Chickens help too if you keep any and can allow them to forage under the trees through the mulch.
Q. There are puckered regions on my apples with a brown corky swelling at the center, what is causing this?
A. This is the result of the apple capsid - a small sap sucking bug that feed on the apple while immature. They kill some of the developing cells and so there's a region that is not so well developed as the surrounding region, the brown corky growth is a sort of tree allergic reaction to the saliva of the bug. The damage is only skin deep and the fruits are perfectly edible. If you have had severe damage in previous years treat by spraying with bifenthrin or pyrethrum at petal fall.
Q. My apples or pears have brown splits or scabs on them
A. Apples - brown shallow splits occur in the fruit which may heal over with a corky layer. This is probably caused by an erratic water supply. The split occurs when the tree has a sudden supply of moisture after a period of drought, the sudden growth splits the fruit which hasn't grown for some time. Regular watering and a good mulch to retain soil moisture is the answer.
Apples - black/brown scabs appear on the fruits with similar scabs on the leaves, though green/gray in color. Fruit may also be small and misshapen, secondarily split and become infected with fungal rots. This is caused by a fungus Venturia inaequalis which over winters on stems and fallen leaves. Fallen leaves should be raked up and burnt or otherwise disposed of out of the garden. Spray the tree with a fungicide containing carbendazim or mancozeb, some apple cultivars are resistant. Trees with overcrowded branches are more susceptible, so pruning to open the crown will help, the disease is more prevalent in damp years.
Pears - black/brown scabs appear on the fruits with similar scabs on the leaves, though green/gray in color. Fruits may also be small and misshapen, secondarily split and become infected with fungal rots. Similar to apple scab, but a related fungus Venturia pirina is the culprit. Treatment as per apple scab.
Plums, Damsons, Greengages and Mirabelles
Their only vulnerability is that they flower early in the spring and the blossom may be damaged by frost reducing that years crop. Birds often eat the flowers which can also affect the crop, I'm fortunate in that there's only a pair of collared doves that get at mine and I can live with the limited damage that they do. They seem to keep others out of the garden and I tend to feed them more at plum blossom time. so they're less likely to go for the flowery salad.
Plums are not self-fertile other than the admirable "Victoria" variety, though given their size it is not too difficult to have 2 or 3 for cross-fertilization in the same garden. Like apples and pears, plums are grafted onto a rootstock which determines their ultimate size, with the grafted portion being the particular variety of plum. Suckers may be produced from below the graft junction which should be removed as seen.
Training and pruning - Being drupes (stone fruits) plums should not be pruned in the winter months as they are susceptible to the fungal disease silver-leaf. The bush form is the easiest to maintain and most effective in the average garden. Over the first three years an open crown with four strong branches should be allowed to develop. Pruning needs only to remove obvious shoots and branches that are damaged, too thin and long, crossing or in the wrong place.
Silver Leaf - This is a fungal disease that affects drupe fruits and plums in particular. The name is descriptive and affected plants leaves take on a silvery appearance due to air being introduced just under the top epidermal surface. The disease usually enters the tree in the winter months often through pruning cuts, so the best defence is not to prune in the dormant winter months, but only when the tree is in active growth. There is no chemical cure for silver leaf, it is the plum tree equivalent of gangrene. Affected branches or twigs should be cut back to healthy unaffected wood with no brown staining. If there is more than about 1/3rd of the branches affected, the tree is best removed and burnt. Any prunings from affected trees should be burnt.
Q. I Was left a plum tree by my father which I planted 4 years ago I don't know a lot about plum trees but this year I had fruit grow which weren't very big or looked edible but the tree has grown to about 12 foot and has a thin trunk which bends over could you tell me if it needs pruning or trimming as I haven't got a clue and it is important to me that I look after it as best as I can your help would be greatly appreciated.
A. Difficult to say really without seeing it. It sounds like it's not happy where it is planted, is it in the shade, poor soil conditions? getting a lot of competition?
What variety of plum is it? Could it be a damson tree? they're small and used for cooking usually. Sounds odd that it's bending over.
So, what to do? Clear the ground around the base at least 2 feet in radius and apply a thick mulch of garden compost. If it needs supporting, then 3 short stakes with long ties each about 2 feet from the trunk and tied quite high up would work or a single 6 foot tall post next to the trunk, but this might damage the roots if you dig or hammer it in.
To be honest a tree that is that condition and is 12 foot tall doesn't have a lot of chance to become normal. It's either in the wrong place or it wasn't staked correctly when it was developing. I assume it has a sentimental significance, so it's worth trying what I've suggested, but if it didn't I be considering replacing or risking moving it to a more advantageous position - a lot of work and no guarantee of success.
I thought I should give you some feed back on the advice you gave me last year.
As advised by you, I cleared the grass for about
2 feet from the trunk and gave it a good dose of
potash last summer. In the autumn I gave it a good
amount of mulch ( rotted compost heap material)
and followed up with another potash feed in the
spring. The results have been tremendous with a
big crop this year, although the size of the plums
has been small (probably due to the real lack of
Q. A young plum tree I recently planted (purchased in a dormant state) does not look healthy and is mildewed, however, what would appear to be a sucker, growing from the base, is doing well and budding as usual. Should I cut back the original tree growth to ground?
A. It's far more likely than not that the sucker is part of the root stock of the plant and not the cultivated plum that you bought it for. Cultivated fruit trees have a well performing variety of top growth grafted onto a wild or semi-wild rootstock. That way you get the quality of fruit and top-growth that you want but with the vigour of native rootstock. Cultivated varieties tend to have fairly poor roots.
If the top growth has died, the sucker will be from the rootstock and while vigorous will produce poor quality fruit. Best to pull it up and start again. Might be worth asking for a replacement from where you bought it if you treated it properly i.e. didn't keep it in the wrong conditions for too long (days or weeks) before planting it.
Pruning should take place in mid to late winter, while the tree is dormant, but after the harshest weather is over. Initial training removes the leader to just above 3 or 4 strong lateral buds, over the next three years, a network of laterals should be encouraged to produce the required 8 - 10. Other branches not selected for the main ones should be pruned to just 4-5 buds in length, The strong laterals should have about 1/4 of the seasons growth cut from them at this time. All cuts should back to outwards pointing buds so that shoots don't cross over. Any dead or damaged wood should be removed all together.
Subsequent pruning is to prevent any shoots taking over from the main branches and to keep fruiting spurs back to 4-6 buds in length. Allowing any longer fruiting spurs will run the risk of them breaking under the weight of the fruit which will damage the shape of tree and allow disease in.
Restorative pruning of neglected trees, should take place over 3 or 4 years if possible. If a tree has been neglected for some time, it will have long pendulous branches that bend considerably under the weight of fruit and some may already have broken. Cut any that have broken to a point beyond the break so the tree can form a clean wound seal. Cut back no more than 1/4 - 1/3 of the elongated branches in any one year to no less than 1/2 of the previous length (unless removed altogether). The tree will probably produce a large number of vigorous shoots in response - many where you don't want them to be. These should be removed or encouraged as appropriate.
Apple Sawfly - In early to mid summer the apples drop soon after forming and have a maggot hole in the side that is surrounded by sawdust like frass (yes - caterpillar dung has a special name! - frass). Control is by picking and destroying affected fruits before they fall off and the moth escapes. If there have been heavy infestations in the past, then spraying with bifenthrin at the point where the petals fall can be effective.
Aphids - Twisted curled or puckered leaves and shoots which on inspection have hundreds or thousands of tiny green, black or pale colored insects. Spray at first sign with a systemic insecticide or your preferred organic alternative.
Codling moth - In mid to late summer small holes in fruits and maggots feeding near the core. Treatment is by the insecticide bifenthrin in early summer followed by another application about 2 weeks later. The timing of the application can be gauged using pheromone traps to see when the moths are most active. Alternatively if you don't want to apply an insecticide, then pheromone traps can catch enough moths if the trees are reasonably isolated to reduce the number of maggoty apples. You will never really totally control codling moths.
Bitter Pit - Small brown indentations in the skin and fruit of the apples. Caused by a calcium deficiency, treat be applying lime to the soil and watering in well (takes over a year to have an effect) or spray with calcium nitrate if available.
Red Spider Mite - Leaves become mottled and fall off, branches can be almost bare except towards the tip. Fine webs are found on the leaves and tiny red mites may be seen, but not easily. Spray with rotenone, malathion or dimethoate in June. This is worse in dry, hot years and rarely a problem outdoors in cooler areas in normal or damp years.
Apple Scab - Black/brown scabs appear on the fruits with similar scabs on the leaves, though green/gray in color. Fruit may also be small and misshapen, secondarily split and become infected with fungal rots. Venturia inaequalis fungus is the culprit which over winters on stems and fallen leaves. Fallen leaves should be raked up and burnt or otherwise disposed of out of the garden. Spray the tree with a fungicide containing carbendazim or mancozeb, some apple cultivars are resistant. Trees with overcrowded branches are more susceptible, so pruning to open the crown will help, the disease is more prevalent in damp years.
Brown Rot - Soft brown spots on the apples and white or yellow fungal growths grow on these. Remove and destroy (not on the compost heap) affected fruits, fallen, on the tree or in store. Spray with a general fungicide or benomyl.
Apple canker - Patches of dead or dying bark on the branches and trunk. Twigs are killed as the diseased bark rings the twig. Cut out and burn affected parts, stumps can be painted with a proprietary canker paint.
Powdery mildew - White powdery deposit anywhere on the tree which distorts leaves and shoots. Remove affected shoots and spray the tree with a general fungicide, benomyl or thiophanate-methyl.
Capsid bug - Puckered regions on apples with a brown corky swelling at the center. Capsids feed on immature fruits so killing some of the developing cells and so there's a region that is not so well developed as the surrounding region, the brown corky growth is a sort of tree allergic reaction to the saliva of the bug. The damage is only skin deep and the fruits are perfectly edible. Severe damage in previous years can be treated by spraying with bifenthrin or pyrethrum at petal fall.
Pears are a cool climate fruit, they require winters that are long enough and cold enough to provide them with a sufficient "chilling requirement" if they are to fruit reliably. They are a little more demanding than apples - a similar cool climate tree fruit - in that they need more sheltered, warmer conditions in the growing season and in particular shelter at flowering time which happens earlier than with apples. Bad weather at flowering time can inhibit pollination and reduce that years pear crop.
Pears are best regarded as not being self-pollinating. Some are (sort of) but almost all do better when they have a pollination partner. The variety "Conference" can form almost banana shaped fruits when self-pollinated for instance, but reverts to the usual pear shape when cross pollinated. Others varieties don't set fruit hardly at all without a pollination partner.
Training and pruning - pears are pome fruits (they have many small pips rather than a single large stone such as plums) and so are pruned while dormant in the winter months. The best time is after the harshest of the winter weather is over, but before the buds break for spring. Winter pruning should be to thin out the fruiting spurs with the removal of one or two larger branches as appropriate to promote younger growth. Fruit thinning may be required sometimes as a very heavy crop may be set.
Pear Scab - black/brown scabs appear on the fruits with similar scabs on the leaves, though green/gray in color. Fruit may also be small and misshapen, secondarily split and become infected with fungal rots. This is caused by a fungus Venturia pirina which over winters on stems and fallen leaves. Fallen leaves should be raked up and burnt or otherwise disposed of out of the garden. Spray the tree with a fungicide containing carbendazim or mancozeb, some apple cultivars are resistant. Trees with overcrowded branches are more susceptible, so pruning to open the crown will help, the disease is more prevalent in damp years.
Aphids - Twisted curled or puckered leaves and shoots which on inspection have hundreds or thousands of tiny green, black or pale colored insects. Spray at first sign with a systemic insecticide or your preferred organic alternative.
Pear Leaf Blister Mite - Like all mites, tiny little creatures (not insects, related to spiders) these cause small raised yellow/green blisters on the leaves. Spray with thiophanate-methyl at the end of March.
Pear Midge - Tiny caterpillars or grubs appear in the small fruits which may fall. Spray with fenitrothion before the flowers open and as they are fading, don't spray while flowers are open as you will kill pollinating insects.
Fire Blight - A very serious disease of many plants, but particularly of pears. The plants look like a fire has been burning below the branches with leaves and shoots first blackening and then shrivelling brown, hence the name. Diseased wood should be cut out and burnt. The disease is most common at flowering time starting at the blossom which goes black and withers. It then passes back to the stems which die back leading to cankers in the bark at the stem bases. Eventually the disease can pass to the trunk which will kill the tree. A bacterial disease with no real treatment other than good husbandry practices such as pruning at the correct time of year and not too drastically at any one time. Pruning tools used to remove diseased wood should be placed in a 10% bleach solution between cuts for at least 5 seconds.
Other Tree Fruit
There are two distinct types of cherry, sweet and acid. Sweet cherries are dessert types and can be enjoyed directly from the tree, the acid types are used for cooking and preserving.
This form is also easiest to net against birds taking the fruit, in many locations if this is an absolute requirement if you are to taste any of your fruit yourself, birds will always take the fruit long before it's near ripe. Sweet cherries need another compatible cherry tree nearby for pollination. They tend to be big trees even on supposedly dwarfing rootstocks.
Mature cherry trees can be a problem if planted in or near lawns as they often have shallow roots that show at the lawn surface. If this is the case, cut the root off near the tree and fill the shallow trench that results with topsoil and apply grass seed. It usually only affects mature trees which can cope with this treatment fairly well.
Bacterial Canker - A disease that affects cherries in particular, and plums to a lesser degree. The tree weeps a quick hardening gum from wounds in the bark, this disease can kill a young tree. Other symptoms are wilting of shoots or blossom and "shothole" damage to the leaves. The leaves develop brown spots which then fall out making the tree look like it has been blasted with shot. The bacteria that cause the disease tend to enter by a wound which then oozes gum. If the bacteria spread around to girdle the branch or twig, the parts above it die.
Peaches and nectarines are respectively downy and smooth skinned versions of the same fruit Prunus persica. Most forms are self-fertile, they prefer warmer conditions, nectarines even more so than peaches. In warm temperate regions the bush form is suitable, in cooler climates, the protection of a sunny wall and/or protection under glass is required, training as a fan is usually the preference here. Other than the preference for warmer conditions of nectarines, cultivation of the two types is identical and where peaches are referred to here, the same applies to nectarines.
Peaches flower in the early spring and so are susceptible to frosts. There are also few pollinators around at this time in cooler climates, so hand pollination, especially if they are being grown under glass is advisable. Fruit thinning may often be necessary as conversely if conditions are good, then peaches will set fruit very heavily. Leaving them unthinned means they are more susceptible to rots and infection, while they produce far more fruits, they are smaller and less satisfactory.
Where space and climate allow, a bush is the preferred shape for peaches allowing about 12ft for the spread of the tree. The aim is to get 8-10 strong branches spreading form a short trunk. Pruning should be kept to a minimum until the bush is ready to produce fruit, confined to removal of dead, crossing or excessive branches. Like other drupes (fruits with a single stone rather than many pips) peaches are susceptible to silver leaf (a fungal disease) and so pruning should be carried out in the early summer and not during winter dormancy.
Peaches fruit on the previous years wood and so once a tree is established, pruning is carried out to remove older growth in favour of newer that will produce fruit the next year.
Peach leaf curl - A disease that peaches and nectarines can suffer from. The foliage puckers, then is covered with a fine white powdery growth, it turns first red, then brown before dropping off the plant. All plants in all areas are potentially susceptible to this fungal disease which is most prevalent in damp areas and particularly in wet growing seasons. Trees growing in protection under glass usually escape this disease. There are no really effective chemical controls and if your peaches have suffered this for a number of years, the easiest answer to to remove your peach tree and grow apricots instead which are hardly touched by the problem at all.
Q. My peaches have diseased leaves and little or no fruit every year, how can I prevent this?
A. Peaches and nectarines can suffer from a disease called "peach leaf curl", the foliage puckers, then is covered with a fine white powdery growth, turns first red, then brown before dropping off the plant. All plants in all areas are potentially susceptible to this fungal disease which is most prevalent in damp areas and particularly in wet growing seasons. Trees growing in protection under glass usually escape this disease. There are no really effective chemical controls and if your peaches have suffered this for a number of years, the easiest answer to to remove your peach tree and grow apricots instead which are hardly touched by the problem at all.