Treat gum flow in fruit trees

Sweet cherries, peaches and apricots are mainly at risk, with many different causes being responsible for the phenomenon. Gum flow occurs primarily at cuts and other injuries to the tree, but also at seemingly uninjured areas of the bark. This tears open and thus offers further pathogens a gateway. Pests can increase rubber flow, but it is not primarily a fungal or bacterial disease. Instead, gum flow is a physiological disturbance of the tree that can result in the death of entire branches and severely compromised crops.

What exactly is the gum flow?

The gumosis occurs primarily in young or very old trees - ergo in specimens that appear from the outset incorrect care measures or poor growth conditions react more sensitively than trees that are at the zenith of their vitality stand. Even the layperson can clearly recognize an outbreak of the disease by the resin-like growths that protrude from the branches or even the trunk. This resin resembles that of conifers in color and consistency, but has a completely different chemical composition. It is mostly dissolved plant tissue, with the wood of the affected tree liquefying and being broken down into various sugar compounds and acids. Gum flow occurs when the metabolism of the tree is disturbed, the causes for this are very diverse.

Damage and effects on the affected tree

Mainly injured areas of the bark, but also parts of the tree that appear healthy on the surface can be affected by the gum flow. After all, injuries are not always recognizable as such at first glance: in many cases, the disruption is a consequence smallest cracks in the bark, caused by tension during frost, or feeding marks from pests such as the bark beetle or the bark moth. A focus of disease develops at the injured site under the bark, where the discharge forms and finally emerges visibly from the inside.

Unfortunately, the gelatinous mass can spread not only outwards but also inwards and, for example, clog important pathways. As a result, the affected part of the tree is no longer supplied with sufficient water and nutrients, so that it eventually dies. As a rule, only individual shoots or branches are initially affected, but in the worst case the disease can spread to the entire tree and ultimately cause it to die off completely. In rare cases, the gum flow also occurs on the fruit.

Gum flow has many causes

Gum mosis is not a sign of a specific disease, but rather a sign of a generally weakened tree. One of the main causes is considered to be heavy, wet soil. Anything else that stresses the tree can also cause or increase rubber flow: wetness, Frost, bark injuries or an inharmonious nutrient supply are also among them Found.

pests and diseases

The parasitic causes for the development of rubber flow are very diverse. Fungal and bacterial diseases, primarily of the bark, but also various animal pests can play an inglorious role here. The disorder occurs particularly frequently in connection with the frequently occurring peach leaf curl, Monilia lace drought, shotgun disease or Valsa disease.

frizz disease

In leaf curl disease, the leaves curl severely, dry up, and eventually fall off. The cause is a fungus that overwinters on the branches and infects the sprouting leaves in spring - especially in rainy weather. Affected shoot tips and leaves should be removed quickly. The use of pesticides is only successful if they are applied at the right time - when the buds swell. It is best to choose a variety of peach that is resistant to leaf curl.

Fungal disease Monilia

The fungal disease Monilia occurs in two different forms: as peak drought and as fruit rot. In the case of peak drought or twig monilia, the flowers and shoot tips often wither abruptly first, followed by the leaves. Rubbery droplets are often seen on affected shoots, later a yellowish to gray fungus lawn forms. Thoroughly cut back affected shoots into the healthy wood and carefully remove dried flower clusters and fruit mummies from the tree and soil. There are approved plant protection products for the treatment of sour cherries, sweet cherries and plums.

shotgun disease

Shotgun disease occurs on plums, cherries, peaches and apricots. Soon after budding, numerous reddish to brown spots appear on the leaves, which break out later. As a result, the leaves appear shot through with holes. The buds, blossoms, fruits and shoots can also show sunken spots, some of which have a red border. However, some stone fruit varieties are considered to be less susceptible and should therefore be preferred when planting.

Valsa disease

There are also varietal differences in the risk of Valsa disease in cherries, plums and apricots, which is favored by heavy, moist soil. It manifests itself as cancerous bark growths with dark, wart-like spots (similar to "toad skin") and rubbery drops. Leaves and fruits wilt on affected branches. Infested parts of the tree should be cut out generously. If the trunk is affected, the only thing that usually helps is clearing the tree.

bark moth

In addition to the pathogens mentioned, pests such as the bark moth can also cause gumosis. This is a species of butterfly with the scientific name Enarmonia formosana, whose caterpillars feed on the bark of various fruit trees and this so strong can damage.

Unfavorable culture conditions

The eruption of rubber flow, but also already the infestation with various pathogens and / or pests can often be attributed to unfavorable cultivation conditions and the associated weakening of the affected tree become. Above all, heavy soil that tends to waterlogging damages the trees growing on it, so that they are no longer able to defend themselves against attackers. But too sandy soils are also not suitable for the culture of stone fruit, instead you should the trees in a deep, humus and nutrient-rich and slightly calcareous soil plant. If necessary, make sure to improve the soil, for example by adding plenty of compost. Even a little sheltered location that is endangered by late frost can be dangerous, especially for sweet cherries, peaches and apricots.

Wrong / insufficient care

Furthermore, inadequate fertilization and thus nutrition of the tree, an improper pruning and incorrect finishing (e.g. on an unsuitable base). lead rubber flow. Health, growth and yield can all be improved by growing fruit trees

• supply with compost and/or potash fertilizer in spring
• fertilize in a balanced way and not with an emphasis on nitrogen
• mulch after the last late frosts
• Water in case of severe drought (especially during fruit development!)
• Protect young trees and early blossoms with fleece during late frosts
• Thin out fruit trees regularly, preferably after harvest

Injuries of various kinds

Also, make sure to avoid or minimize injuries of all kinds - for example, through excessive or improper pruning or late frost. to supply them correctly immediately. Many stone fruit varieties are quite sensitive to frost and need winter protection. But even if they should be frost hardy, a frost that sets in late in the spring can have serious consequences: The already "full of juice" standing tree gets the finest cracks in the bark due to the strong cold, which in turn leads to a weakening and thus a cause for gum flow can.

Effectively treat rubber flow – it doesn’t work without pruning

On trees prone to gum flow, strong shoots are best pruned back to cones. While the gardener should generally not leave any cones or stubs, there are some exceptions with stone fruit (and soft fruit too). When cutting away, pruning back and deriving strong shoots, it is best to leave cones about 20 centimeters long above the cutting point. The gum flow then occurs at the spigot, which dies over time and can be removed but does not damage the remaining drive portion. In addition, stone fruit at risk of gum disease should preferably be pruned in summer immediately after harvest. A cut at this time promotes rapid wound healing and slows down growth. A winter cut, on the other hand, should be avoided if possible.

Prevention is better than cure

Gum flow must always be treated as soon as possible, otherwise large parts of the affected tree may die. Therefore, carry out regular checks and not only look for signs of gumosis, but also for a possible fungal, bacterial or viral infection or infection. a pest infestation. In addition, make sure that the fruit trees are carefully cared for and cared for in a species-appropriate manner and take other preventive measures.

Pay attention to the right location when planting

The best prevention is to plant fruit trees in a suitable location from the outset. Experience has shown that cherry and plum trees in particular thrive much better on neutral to alkaline soils than on acidic ones, and are therefore less susceptible to plant diseases. Peaches, nectarines, and apricots do best where it's warm, sunny, and sheltered—not in vain have these frost-sensitive fruit varieties in Germany, especially in the wine-growing regions established. On the other hand, if you live in a climatically unfavorable region, make sure you have suitable frost protection during the winter months and especially when there is a threat of late frost in spring.

Plant less disease-susceptible varieties

In addition to a suitable location, you should primarily plant varieties that are less sensitive or less sensitive. are even resistant to many gum flow-causing diseases. This eliminates a common cause from the outset. In the following overview we have put together some recommendable, less disease-prone stone fruit varieties for you.

Robust plum varieties for the garden

• 'Hanita': also for rough situations, very little vulnerable to Sharka
• 'Bühler Frühzwetschge': little susceptible to Sharka and other diseases
• 'Jojo': resistant to sharka
• 'Katinka': not very susceptible to sharka
• 'Ontario plum': not very susceptible to sharka
• 'Opal': less susceptible to Sharka
• 'The Czar': very robust, not susceptible to Sharka
• 'Bellamira': little susceptible to sharka and other diseases
• 'Mirabelle von Nancy': little susceptible to Sharka and other diseases

Robust sweet cherries for the garden

• 'Burlat': very robust, maggot-free
• 'Regina': very robust, fast-growing
• 'Kordia': low site requirements

Robust sour cherries for the garden

When choosing a suitable sour cherry variety, in addition to taste preferences, you should pay particular attention to its resistance to Monilia peak drought. The popular morello cherries, for example, are considered to be very susceptible to monilia. On the other hand, varieties such as 'Morellenfeuer' and 'Morina' are less susceptible, and even 'Ludwigs Frühe' and 'Safir' are resistant.

Robust peach varieties for the garden

In general, peaches are very sensitive and are particularly prone to cracking. On the other hand, varieties such as 'Benedicte', 'Kernechter vom Vorgebirge' (also known as 'Red Ellerstädter'), 'Revita' or 'Red Vineyard Peach' are considered to be moderately susceptible to disease.

Cut fruit trees properly and treat wounds

During the main growth period, the tree has the most energy, cell formation is more active and the wounds overgrow better and faster than in winter. In addition, when the canopy is fully unfolded, no more sap drips out than the cuts. For these reasons, pruning is preferable, especially after harvest. The correct wound treatment after the cut is also very important: smaller wounds heal in usually by itself, but as soon as they are larger than a two-euro piece is a follow-up treatment sensible. To do this, cut the edges of the wound smooth with a sharp knife and spread them with a suitable wound sealant. Wounds treated in this way quickly begin to overflow from the edge; new cells form from the cambrium, the dividing tissue under the bark.

Lime endangered trees in autumn

You can avoid cold damage and damage from pests by liming your fruit trees in autumn. To do this, mix lime powder with water until creamy and spread the mixture on the tree trunk with a thick brush. The white coating reflects the sunlight and thus reduces extreme temperature fluctuations in the wood - with the result that fewer frost cracks occur.

Conclusion

The so-called gum flow or gumosis is not a plant disease in the actual sense, but rather a symptom of a sick or weakened tree. The causes of this phenomenon are very diverse: The causes can be pathogens and pests as well as unfavorable location and growth conditions, wrong or insufficient care as well as frost damage and other injuries in come question. Infested trees should be treated immediately, as the resin-like, mostly colorless to amber-colored discharge clogs the pathways and can lead to the death of large parts of the tree. In principle, almost all deciduous trees can be attacked, but gummoss is usually found more frequently in stone fruit of the Prunus genus.

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