Clematis - Flowering Vines

Tree Fruit Pests and Problems

Flowering shrubs and trees

 

Problems with fruit have to be the most frustrating problems of all, fruit are the whole point of the exercise and if you can't get any, then there's no point in giving the tree space in the first place. These are some of the commonest ailments that might affect a fruit tree.

The ends of many new shoots on my fruit tree are dying back

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 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. 

Not to be confused with fire blight.

There are loads of strong vertical shoots growing from my tree

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.

My tree looks healthy and produces flowers, but never fruits

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. 

My tree looks healthy but never even flowers, let alone fruits

It may be that the flowers are being killed as buds by frosts before they get a chance to develop, do you live in a frost pocket? Somewhere that has many frosts at flowering time? Next year (!) go and look carefully when you see some growth on the tree and look for developing flower buds. There's a possibility that birds may be eating the buds, though they tend not to get every single one (unlike frost) and a few survive.

If there are no buds to be seen, it may be that your tree is too happy. When trees are young they put their energy into growing into the available space before starting to fruit, why produce a couple of dozen this year when you can produce a hundred or more next? If the shoots are growing strongly upwards and look a particularly healthy shade of dark green, then this is probably the case. Stop feeding the tree if you are doing so. The branches can be bent down with weights which will help, plastic bottles of water on strings are effective if odd looking - "it's my modern art installation". Otherwise it's a case of waiting for the tree to stop behaving like a teenager growing upwards and thinking of itself and start to find a nice pollinator and have a family instead.

My trees crop heavily some years, but then produce little or nothing the year after

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.

How can I prevent birds from eating my fruit?

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 through 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.

My apples, apricots, pears or plums are maggoty

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). Sawflys 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.    

There are puckered regions on my apples with a brown corky swelling at the center

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. Severe damage in previous years can be treated by spraying with bifenthrin or pyrethrum at petal fall.

My apples or pears have brown splits or scabs on them

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.

My peaches have diseased leaves and little or no fruit every year

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.

Should I apply a tar-oil winter wash?

This is an insecticide applied to fruit trees in the dormant winter months. It is useful to eradicate pests such as aphids that overwinter in nooks and crannies in the bark of the tree trunk, branches and twigs. It kills leaves on contact and so must be kept clear of evergreen plants and not used on deciduous plants before they drop their leaves.