realenglishfruit

Top fruit tree growing advice and information from Real English Fruit

Category Archives: Pest and disease control

Video: Peach-leaf curl – prevention

Peach-leaf curl is a disease, caused by the fungus Taphrina deformans, that can be recognized because the leaves of the tree curl up and take on a reddish colour. It is very damaging to the tree and so steps should be taken to avoid it. The best system would be to grow peaches in a glasshouse, but when the trees are outside, ideally against a wall on the south side, what is really important is to ensure that during winter and spring, the buds and the wood remain dry. Here you can see that Dan has built a simple frame around the tree so that he can cover it with tarpaulin or some other type of waterproof sheet. Openings at the side encourage the wind to blow through the tree, helping to keep it dry. Once the flowering is over, at the end of May, you can safely remove the cover. If your trees suffered peach leaf curl last year, you have to ensure that all the affected leaves have been removed, because the spores on affected leaves are still very infective even after the leaves have been cut away from the tree and could easily affect it again. More information on peach leaf curl here.

Video: Tree bark, tree health, and canker treatment

It is a good idea to take a look at your tree at regular intervals and assess its overall health. The colour of the bark provides a good indication of health. If the colour of the trunk and main limbs is a bright grey shade, you can be sure that there are no drainage problems, and the root system is happy. If on the other hand the colour of the main trunk is reddish, this is an indication that the tree has been waterlogged, and the root system has suffered. In this case the only solution is to try to improve the drainage.

At this time of the year, April, you can check for other diseases that are easier to locate when there are still no leaves on the tree, such as bacterial canker and ordinary tree canker which is caused by a fungus. If you find canker, use a special curved canker knife to cut it out. Cut away the brownish, canker-affected parts until the wound is entirely green. Then coat the wound with anti-fungal paint. The tree will heal the wound itself.

Tasks for garden fruit trees in June – part 2

Check your pheromone traps for codling and plum moths. Renew the lure if necessary. Start spraying the apple varieties which have a tendency towards bitterpit in the fruits. Apply fruit nets where bird trouble might occur, cherries in particular. Continue thinning out the fruitlets to doubles or singles. Remove scabby fruits at the same time. Start the summer pruning programmes of plums, cherries and greengages. The same applies to nectarines, peaches and apricots. Hang rolled up corrugated cardboard in the trees to attract the caterpillars which would otherwise damage foliage and fruits. Regularly inspect and renew when caterpillars are caught. Deal with aphids if present in too large a number in folded-up shoot tips. Do not let the trees dry out. This in particular applies to potted trees. Continue with foliar feeding if foliage of the fruit trees is not up to the mark. Make a start on preparing the ground where new trees will be planted in the autumn.

After natural drop, in June it is advisable to reduce the number of fruitlets in a group like this

After natural drop, in June it is advisable to reduce the number of fruitlets in a group like this

Peach leaf curl disease

Peach leaf curl disease (Taphrina deformans) is the main issue you have to be aware of with peach, nectarine and apricot growing. I f you follow my guidelines you will have no trouble with this fungal disease.

Apricot has the same trouble, but in a milder form. However, if you cover your peach tree or your apricot tree with a double layer of garden fleece from late January until the middle of May, every year, or bring the potted tree indoors during the winter months, the disease cannot develop.

Peach leaf curl

Peach leaf curl, photo courtesy of Scot Nelson/flickr.com

The fungus Taphrina deformans attacks the tree species of peach, nectarine and apricot.

The symptoms are the development of large reddish blisters on the leaves. The tree is seriously weakened as photosynthesis by the leaves is seriously affected.

Eventually the tree is starved to death as it is no longer able to make essential carbohydrates through photosynthesis. Leaves tend to fall prematurely and growth comes to a full standstill.

The fungus attacks the tree from early February until the middle of May. After May the fungus is no longer producing spores and therefore cannot cause new infections.

How to avoid peach leaf curl disease

There are various options for controllilng this fungus. Some varieties are more resistant than others. However this is no help if you already have to cope with this problem.

Actions to be taken immediately are the complete removal of leaves affected. This applies to the fallen leaves as well as the affected leaves that still attached to the tree. Make sure the leaves are all collected up, put in a plastic bag and then put in the non-recycling bin. Make sure the tree is well watered and does not stand in a carpet of weeds and grass. Apply a full watering can of water once or twice a week, particularly during the summer months. Mulch the tree with well rotted farmyard manure. The area to be mulched must be of a minimum size of one square yard.

Never let the tree go short of water! By late January cover the tree with a double layer of garden fleece. Fasten the fleece securely. Make sure the wind cannot affect it or lift it off. Keep your eye on the tree and if a tear develops in the fleece after particularly bad weather, repair the damage properly. This fleece needs to stay in position until the second week of May. After that time, carefully remove the fleece.

Never prune the tree during the autumn and winter months when the leaves have fallen. It is at that time that new infections occur very quickly. Prune during the middle of May or during late August, making sure the old wood is removed to make room for new shoots to form. This is essential as the fruits of peach and nectarine are formed on one year wood only. Seal the pruning cuts with “Prune and Seal”, a compound available from your garden centre. The foliage of a well pruned tree dries up quickly, with less chance of new infections.

If it is not possible to cover the peach tree, to avoid the disease you can spray with copper during the first week of February and repeat the spray 14 days later. Follow the instructions on the packet in detail. Garden centres stock it. At leaf fall in late November put on another spray of copper.

Peach leaf curl disease is spread by rain droplets. The fungus over-winters and is hidden in crevices of the bark and between the bud scales. Therefore consider planting a peach tree in a 15 to 18 inch diameter pot. By the end of January, wheel the potted peach tree into a cold shed or a cold green house or a cold poly tunnel. In that way no fleece is needed as the tree is sheltered from the winter rains. By the middle of May it is safe to take the pot outdoors again. Then position the tree in a warm sunny place and water it weekly or twice a week when very warm weather is occurring. Never let the tree go short of water as it will surely die.

Feed the tree monthly with a suitable foliar feed , obtainable from garden centres.

May orchard update – grubs in plums or apples

If last year you found grubs in your plums or apples, now is the time to do something about it. Depending on the severity of the problem, the correct pheromone trap will reduce or eliminate the damage.

If you have plum trees, please make sure a pheromone trap is placed in the tree. This will reduce or eliminate damage by the plum moth. The same principle applies to apple trees, but in this case the trap to be hung in the tree is the codling moth pheromone trap.

Continue to water young fruit trees. Make sure the one square metre of clean soil around the trunk of the fruit trees stays without grass and/or weeds. This is to ensure that your watering is to the benefit of the young fruit trees, and not the weeds and grass.

Pheromone trap, photo courtesy of MPaola Andreoni/flickr.com

Pheromone trap, photo courtesy of MPaola Andreoni/flickr.com

Death of established fruit trees

Apart from old age, some times trees die unexpectedly, even at a young age.
The death of fruit trees can be caused by several factors:

1) Collar rot
2) Armillaria root rot
3) Soil contamination with aggressive chemical substance
4) Tree canker
5) Tree trunk restriction
6) Drought.

Drought is often the cause if the trees are not cared for and the competition of grass and weeds is too severe, combined with a long dry period. If this is not the case, then a careful examination of the tree will need to be carried out.

Examine the tree trunk very carefully. Is there an obstruction that has grown into the tree trunk and is causing severe restriction? If this is the case some new and healthy-looking young shoots will appear below the restriction. This will also be the case if tree canker is girdling the tree. Next, use a sharp knife to peel back a portion of the bark on the trunk. If no healthy yellowish cambium under the bark is present and the wood is brown and dead, then points 1, 2 or 3 , as mentioned above, are the most likely causes of the tree trouble. An example of Point 3 is when a chemical substance such as concentrated weedkiller has been poured onto the ground next to the tree.

If this is not the case, we will then be left with points 1 and 2 as the most likely cause. In both cases, the chance of the trouble spreading to other trees becomes an issue, because the fungus remains active on the tree roots. If it is the armillaria fungus, the toadstools will appear around the trunk in the late autumn period. However the bootlace-like fungal threads will then already have arrived around the roots of your nearest fruit tree or ornamental tree. In that case grubbing the tree in total is the only option.

Summarising, if after a detailed examination, you find that the likely cause of tree death is armillaria, then you will have to grub the tree immediately, remove it off the site, roots and all, and burn it, as soon as you can. Armillaria fungus is very active in finding and infecting its next victim.

Whatever the outcome of your examination, my advice is to always use new, clean soil if you want to replant a fruit tree this coming autumn. Taking in consideration crop rotation principles, do not plant apple after apple or pear after pear etc. Vary the tree types. So, for example, apple after pear will be fine.

Armillaria

The illustration above is from “The Book of gardening: a handbook of horticulture”, 1900, edited by William D. Drury. It is accompanied by the following text:
“Armillaria mellea (Agaricus aielleus) This is a most destructive fungus found upon living ornamental trees, such as Conifers, as well as upon orchard trees. It is responsible for the disease known as Tree Root Rot. The fungus is most abundant, and is found both as a saprophyte and as a parasite. The clusters of Mushrooms at the base of trees are very familiar; they are, moreover, conspicuous alike as to size and colouring. The cap is of a pale yellow, with darkish scales upon it; the stem is also yellow. The fungus finds access to healthy trees either by means of its spores, which germinate on an injured part of the bark; or by means of the very peculiar mycelium, which is black and stringlike, and always endeavouring to penetrate the roots of healthy trees. The only thing that can be said in favour of this fungus is that its sporophores, or Mushrooms, are edible, though not particularly rich in flavour, being somewhat strong. Care should be taken to carefully remove and either eat or burn all specimens of the fungus, so that the danger of trees being infested by the spores which are shed is minimised. The mycelium found under the bark is white and felted. Once a tree has been badly attacked nothing can save it from destruction, as the mycelium spreads under the bark with considerable rapidity. Preventive rather than remedial measures should be adopted. These may well consist in the removal of all dead stumps on which the fungus is growing as a saprophyte; and in isolating the infected live trees.”

Weekly update for the fruit garden – fourth week of August 2015

Wasps have been a real hindrance all round, due to the changes in weather patterns. As a result, fruit which has been damaged by wasps or birds is now showing the usual signs of brown rot developing. It is very important to remove this fruit and dispose of it. Irrespective of whether the fruit still is hanging on in the trees or has already fallen on the ground, if it is left there, the spores of the fungus may be developing on the remaining fruits. Orchard hygiene at this stage needs to be taken seriously.

If the trees have been growing strongly, this is the right time to carry out summer pruning. Details of the summer pruning technique are explained in the Pruning Section on the website www.realenglishfruit.co.uk

This is also the right time to prune away surplus growth on trees which are being trained as cordons, fan or espaliers or step-over trees.

Photo courtesy of LHG Creative Photography/flickr.com

Photo courtesy of LHG Creative Photography/flickr.com

Weekly update for the fruit garden – third week of August 2015

Apples:

Today we picked some good sample of Discovery apples. During the first week of June, we thinned the clusters of the young fruitlets to two fruits per cluster. The effects of this are now, at picking time, very evident. The fruits are of beautiful colour, decent size and very crisp. It is always right with early maturing varieties to thin out the fruitlets, EARLY in the growing season, if you like crisp fruit with a good flavour. Never store early fruit with long term storage fruit. Early varieties produce lots of ethylene and therefore reduce the storage life of all the surrounding fruits.

Make a regular check and remove any fruits showing brown rot. Do not drop this fruit on the orchard floor. Spores easily spread and will infect other fruits still on the trees.

The rewards of a well-tended orchard

The rewards of a well-tended orchard

Raspberries:

Continue regular picking of the autumn–fruiting raspberries. Cut out the old canes of the summer fruiting raspberries. Tie in the new shoots.

Wasps, flies and over-ripe fruit

At this time of the year, wasps and flies can be a great problem with plums and cherries and later on with apples and pears. These insects are particularly interested when fruits are becoming OVER-RIPE.

Therefore do not delay in picking the fruits when ripe. Secondly, make sure local wasps’ nests are dealt with. Wasp traps are only partially effective. Clearing the nests in the vicinity is the best solution.

Photo courtesy of Ervins Strauhmanis/flickr.com

Photo courtesy of Ervins Strauhmanis/flickr.com

Pigeon damage on plums and greengages

Photo courtesy of Marle Hale/flickr.com

Photo courtesy of Marle Hale/flickr.com

It is at this time of the year, when the first newly emerging little leaves are a great attraction in all areas where pigeons are present in great numbers, where field rape is grown. The pigeons show a great desire to vary their food source. After having grazed the rape fields, the pigeons will move for a while to the nearest hedge cover. From that point they will attack any type of plum or green gage, severely damaging any blossom or young green leaves.

The net result is that the crop prospects of those trees will be set back greatly and may result in no crop at all. Anything that can be done to scare the pigeons away is worth trying. A mixture of various deterrents is better than just one. Click here to read about one method of protecting the trees.

The length of the period during which the trees are at risk will greatly depend on temperatures and type of weather. A long cold spell is the most damaging period. This season is likely to be a bad season as warm spring weather seems not to be expected just yet, according to the 10-day forecast by the weather experts.