Fight pears rust: Sprays and home remedies for pear grid

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Fight pears rust: Sprays and home remedies for pear grid: sprays

The pear grid is a fungus of the order of the rust mushrooms, the plants of the kind Pyrus (pears) and Juniperus (juniper) attacks. Unique to the fungus is the annual change of hosts, because over the winter, juniper plants are attacked, while in summer pears are delivered to the pear rust. In order to kill the fungus, special sprays are available that effectively counteract the infection.

Infection chain of pear lattice

The pear rust (Gymnosporangium fuscum) is a fungal disease that undergoes a unique course over the year, during which several host changes occur. This course is called an infection chain, which describes exactly which plant species are affected by the rust fungus and when:
  • Winter to early spring: the Juniper species Juniperus chinensis (Chinese Juniper) and Juniperus sabina (Sweet Tree), more rarely Juniperus scopulorum (Rocky Mountain Juniper)
  • Spring to early autumn: pear trees (bot.Pyrus), rare quince (offered by Cydonia oblonga)
The spores specifically attack the juniper trees and shrubs of the species mentioned and spread in these. The infection manifests itself in nodular branch thickening and large spore beds. These are as follows:
  • Color orange
  • Consistency: rubbery, bile-like
  • stand in individual thickenings
  • become slimy throughout the year
The spore camps of Gymnosporangium fuscum are easily recognizable and through them the fungus attacks its next target, the pear trees. Interestingly, the juniper plants are not damaged by the fungus, they serve only as a kind of intermediate host. Formed are basidiospores, which are distributed from spring by winds within a radius of 500 meters and settle on the leaves of the pear trees. There they begin to infect the pear and thus continue the chain of infection:
  • Leaf top becomes spotty
  • Stains are orange-reddish
  • Spots get bigger over the months
  • Summer spores are formed, which affect the tree even more
  • now pollinator insects like bees are attracted by the formation of a false nectar
  • the spores cling to the animal and carry it on
  • in late summer, the fungus spreads to the underside of the leaf
  • It is up to 1.5 centimeters large, oval spore bearing formed in brownish color
  • These break up at the beginning of winter and spores are released, which in turn infest juniper plants

Pear - Pyrus

Through this chain of infection, the rust fungus can easily preserve itself and use every season to its advantage. This development must be taken into account when combating the pear grid, as this is the only way to effectively combat the infestation. Particularly young pear trees can be greatly restricted in their growth by the rust fungus, while older specimens are only weakened. The result of this is often an over the years intensifying stunted growth, which results in a poor harvest. Do not confuse the infestation with the fungus, but not with the pearpox mite, which has a similar damage pattern, but without the spore storage.
Tip: Even if your pear is covered from pear grate from top to bottom, you should not just throw away the fruit after harvesting. The fungus only affects the leaves of the tree and not the fruits that can still be consumed and pose no threat to your health.


Fighting the pear rust after attacking the pear trees is extremely tedious and difficult, so you should curb possible infestation as early as possible. If the chain of infection described above is interrupted, the spores can not identify the trees and your pears are safe without much effort. For prevention different methods are available:
Treat the intermediate host
To prevent the spores from spreading further, it is necessary to curb the infestation and prevent the spores from rising into the air again from spring onwards. For this reason, once a juniper of the above species is in their garden, check it for fungus. If this shows the characteristic excesses, you should remove all affected areas thoroughly. Just remove them with a clean pruning shears or pruning shears.
Remove intermediate host
Extremely effective is the complete disposal of the host, especially if it is heavily infested. If the infected juniper is removed from the immediate vicinity of the pears, the infection can be largely contained. But always make sure that even far away junipers can still distribute their spores, so it is also possible to remove the pear tree so that the spores do not multiply over the summer host.
Replace intermediate host
Who does not want to give up a juniper in the garden, should opt for another species that is not prone to the rust fungus. This includes:
  • Juniper community (bot. Juniperus communis)
  • Gray shrub juniper (offered by Juniperus media 'Hetzii')
  • Coastal juniper (bot. Juniperus conferta)
  • Virginia juniper (offered Juniperus virginiana)
  • Scaly juniper (bot. Juniperus squamata)
  • Creeping juniper (bot. Juniperus horizontalis)
Alternatively, you can also choose pear varieties that are not as sensitive to the mushroom:
  • Condo
  • Countess of Paris
  • Stuttgart Geisshirtle
  • Upper Austrian wine pear
  • Trevoux
  • Gellert
Although these pear varieties may still be affected by pear rust, they are much more resistant to Gymnosporangium fuscum and therefore require a longer time to infection. More effective, of course, is the exchange of juniper species.
Plant strengtheners
It is recommended to treat pears with plant strengthening agents from the first expulsion of the leaves in spring. Horsetail extract, which you can buy from manufacturers such as Neudorff or Aries, is best suited for this purpose. If you want to make the extract yourself, you can too. This home remedy is the only one that works effectively to prevent pear rust:
  • Ingredients: 10 g of dried or 100 g of fresh horsetail (offered by Equisetum arvense) per 1 l of water
  • cut the blades of grass small
  • put this in a pot of water
  • Soak for 24 hours
  • then boil for 30 minutes
  • then transfer through a sieve into another container
  • Mix the broth with water in the ratio 1: 5

Pear - Pyrus

The finished extract is stored properly for several months. Spray with these the pear trees four times at intervals of one to two weeks.
Reduce nitrogen
Use fewer fertilizers that contain a lot of nitrogen. These weaken the pears for a long time and thereby enable an infection that strikes faster and the trees to the mushrooms defenseless.
Remove leaves
If your pear tree has been attacked by the mushrooms, you should remove all leaves as soon as possible and dispose of them on the compost. The less weakened leaves are on the tree, the stronger the plant and the danger of a rapid spread of infestation is prevented. Do not worry, the discarded leaves can be composted, as the spore beds are empty over the winter.
Tip: If one of your neighbors has a juniper in the garden, be sure to discuss it with you for possible disposal or treatment if the plant is affected by pear rust. Only then can you prevent a possible infection.


Once pear rust has attacked a pear tree, it is stubborn and can only be combated with difficulty. Home remedies do not work at all with this rust mushroom and for this reason you must change over to finished spraying means. For gardeners in the home since 2010, there is only a single fungicide on the market, which acts against the rust fungus:
  • COMPO Duaxo Universal Mushroom-free
  • available in 75 and 150 ml
  • Cost: 12 - 17 euros
This universal fungicide can be used not only against the pear grid, but also for other crops such as roses or herbs. This is administered to the tree in time before the attack by the spores and thus they have no chance to infect the bulb. A big advantage of the agent is the depot effect, by which the tree is protected over a longer period of time. You use the remedy as follows:
  • Mix 10 ml of the product with 1 l of water
  • put the mixture in a squeeze bottle
  • shake them
  • Spray the plants thoroughly in the evening
  • The leaves should not be damp
  • Do not spray in the wind, that could go unnoticed
  • Be sure to thoroughly handle the undersides of the leaves
  • thus you increase the effect of the spray
  • You should also be careful not to spray near water
  • the fungicide is detrimental to aquatic life
An alternative to this are scarf sprays, such as Ectivo Fungus Free from Celaflor. This should only be used for prevention.

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