Recognize, treat and prevent

the essentials in brief

• Mushroom called Gymnosporangium sabinae causes pear rust
• Infection always occurs via various juniper species as an intermediate host
• Fungal spores migrate from juniper to pear leaves in spring
• The spore transfer takes place back in autumn, as the spores overwinter on juniper
• Damage is characteristic; control is only necessary in the event of severe infestation

What is pear grate?

Of the Pear grate is a plant disease caused by the fungus Gymnosporangium sabinae. The parasitic pathogen infects already sick or weakened plants by settling on you or on earth and from there penetrates the plant tissue and moves away from it nourishes. Like all mushrooms, the pear rust spreads through so-called mycelia (d. H. the fungal network) as well as through spores.

How is the pathogen transmitted?

Gymnosporangium sabinae overwinters in juniper

This section is important in order to be able to combat the disease properly - the fungus not only affects pears, but also takes a detour via an intermediate host. The transmission only works with the help of the host change, which is why you can prevent (re) infection of your pear by switching off the intermediate host.

This intermediate host consists of various types of juniper (Juniperus) that have to stand near the pear tree and from where the spores keep spreading. The life cycle of Gymnosporangium sabinae is as follows:

• overwinters in juniper
• forms its spores here
• Spores are transmitted to pear leaves by wind, insects, or birds
• The time of this infection is in spring, when the leaves begin to shoot
• here again spore formation takes place in autumn
• these are again transferred to the juniper
• With the fall of leaves in autumn, the pear tree gets rid of the fungus again
• the game starts again in spring

On the pear, the fungus only sits on the leaves, only the junipers affected are permanently ill.

It is transmitted through ornamental junipers

However, Gymnosporangium sabinae does not like every juniper. Species such as the native common juniper (Juniperus communis), which comes from North America Creeping juniper (Juniperus horizontalis) as well as the scaly juniper (Juniperus squamata) remain of the Mushroom spared. Juniperus communis in particular proves to be extremely resilient over and over again.

Frequent Carrier many imported ornamental juniper species that are in the Planted in gardens, green spaces and cemeteries in recent decades because of their vigor became:

• Moss juniper or sedge tree: Juniperus sabina, evergreen dwarf shrub, particularly susceptible to Gymnosporangium sabinae
• Chinese juniper: Juniperus chinensis, popular ornamental juniper, frequent intermediate host for pear grids
• Pfitzer juniper: Juniperus pfitzeriana 'Wilhelm Pfitzer', variety of the Chinese juniper
• Virginian juniper: Juniperus virginiana, also called Virginian cedar respectively. Red cedar is often praised as a climate change tree

The species mentioned are commercially available in different cultivars, although not every cultivar is equally susceptible to infection with the pear grate. For you, this knowledge means that if pear rust appears on your pear trees have to decide: Either the juniper has to give way or the pear, because that's the only way to get rid of the pathogen fight.

Digression

How dangerous is the pear grid actually?

Damage - How to recognize an infestation with pear rust

Small orange spots on the leaves are the first signs of an infestation

The pear is infected with the pear grate around the time the tree is in bloom between May and June:

• initially small orange or yellow spots on the upper side of the leaves
• increase in the course of summer
• different degrees of infection possible
• sometimes only a few leaves affected, sometimes severe attack with almost all leaves
• in the case of heavy infestation, the tree looks more orange-red than green in autumn
• later wart-like nodules on the underside of the leaves
• these are spore bearings
• gradually tear open to form a meshwork and are distributed by the wind

However, an infection with the harmful fungus is noticeable differently on the affected juniper. Here you identify the disease by the following features:

• recognizable from mid-April
• initially, branches of the infested juniper thicken
• later wart-like growths appear there
• these bear brown, later bright yellow, spore bearings
• approx. one to two inches tall
• shine when wet
• Infection shows itself only on the branches

Infected junipers can usually live quite well with the fungal pathogen, only with a very strong infestation and the associated weakening does the wood die after a few years.

Effectively prevent pear rust

Nutrient-rich, healthy soil is the basic requirement for healthy trees

Once a pear is infected with the pear grate, the infection will keep recurring - the disease To combat effectively, you would finally have to find its originator, the also infested juniper, and remove. However, this is not always possible, after all, the culprit can hide in an unknown garden a kilometer away.

In this case, the only thing left to do is to strengthen your endangered pear tree. In this way, it survives an infection better and is less weakened by the action of the fungus. Suitable strengthening measures are:

• Creation and maintenance of healthy soil
• Strengthening the soil life
• both are done through the use of organic natural fertilizers
• as well as by avoiding artificial fertilizers and chemical pesticides
• Compost is particularly suitable for strengthening microbial life in the soil
• just use nitrogen sparingly fertilizeas the nutrient promotes fungal infections
• therefore beds with strongly consuming plants (e. B. Do not create vegetable patches in the immediate vicinity of pear trees
• In addition, never cut pear trees before they shoot, this weakens them
• Always cut back in summer, as wounds can now be closed better
• Strengthen the defense of the pear trees with plant strengtheners
• Home-made horsetail manure is particularly suitable
• Purchased horsetail or algae extract is also suitable

The manufacture of Horsetail manure is very simple, even if it is quite odorous. It is best to place the container with the use during the fermentation process where its vapors are not too disturbing. With a handful Primary rock meal also bind the smell.

How to make the plant-strengthening brew:

1. Pick or cut a kilogram Field horsetail.
2. Use the whole plants, with no roots.
3. Chop the horsetail as finely as possible.
4. Put the plant material in a plastic or enamel bucket.
5. Do not use a metal pail as this can cause undesirable chemical reactions during the fermentation process.
6. Fill up with ten liters of soft water, preferably rainwater.
7. Stir well.
8. Add a handful of bedrock flour.
9. Cover the container with a piece of fine wire mesh or a piece of jute cloth.
10. The cover is designed to prevent animals from drowning in the manure.
11. Put the manure bucket in a dark and warm place.
12. Leave it there for about a week.
13. Stir vigorously every day.
14. The liquid manure is ready when it becomes frothy.

Now filter the finished horsetail manure and immediately fill it into a suitable container, preferably made of plastic and easily closable. It stays in this for a few weeks. Water the pear tree with a watering can full of the liquid manure every 10 to 14 days from the budding in spring to the leaf fall in autumn. The tree is not only strengthened, but also supplied with valuable nutrients.

Which types of pear are susceptible to infection and which are not?

Some Pear varieties are more prone to the disease than others

The incidence of infection can also be contained by planting less susceptible pear varieties. The popular varieties of Pyrus communis listed in the following table are considered to be particularly susceptible or little susceptible to pear rust.

But be careful: “Not very susceptible” does not mean that the pear trees mentioned cannot still get sick from the pear grating - there are no resistant varieties on the market yet. So the pear grating should be well represented around you - for this purpose before planting ask the neighbors around a pear tree - another fruit tree might be the more sensible one Choice.

Digression

Other endangered plant species

Fight pear rust - methods and means

The pear grate can only be actively combated with a pesticide approved for home and hobby gardens: Duaxo Universal Mushroom-Free from COMPO (also under the names Duaxo Rosen Mushroom-free or Duaxo Universal Mushroom Spray) is the only one approved against this fungus Pesticides.

However, its use has numerous disadvantages and should therefore not be done rashly:

• it has to be sprayed every year as long as the guilty juniper has not been removed
• causes resistance after repeated use, i. H. at some point no longer works anyway
• gets into water (u. a. also into the groundwater) and is not broken down there
• is extremely dangerous for many animal and also human garden dwellers
• endangers the ecological balance

So instead of spraying poison on the pear tree every year (because it is nothing else), you better find the cause and eliminate it. A simple pruning of the infested juniper, as is often recommended, is usually not sufficient. The fungus sits not only in the visibly infected branches, but also deep in the apparently healthy areas.

When is it really necessary to fight the disease?

Action is only required when the infestation gets out of hand

If your pear tree has only a few leaf spots, you don't have to act - the pear grate mushroom and pear trees can, as long as the ecological balance is maintained and the pressure of infestation does not become too strong, with each other without any problems get along. You should only take action in these cases:

• Infection occurs several years in a row
• and very pronounced
• several spots per sheet
• premature leaf fall
• Tree is more orange-red than green in summer

If the disease has broken out, there is nothing more you can do - only preventive measures in the spring can prevent a renewed infestation. Incidentally, young pear trees are also endangered. While an older, established specimen has a lot of defensive powers to oppose the fungus, young, not yet robust trees quickly perish. So in this case, you definitely need to act!

frequently asked Questions

Are there any home remedies that can be effective against pear rust?

No, once the disease has broken out, no commercial pesticides (with the exception of those mentioned in the article) nor any home remedies will help. You can only treat pear rust by locating the carrier of the infection and making it harmless. In addition, the affected or endangered pear with Herbal manure be strengthened - sprayings with silicic acid-containing agents help against the infection in the spring.

Can the typical symptoms of the disease also be confused with other infections?

For the inexperienced, the pear grate can easily be confused with other fruit diseases such as fire blight or pear pox mites. Pearpox mites are pests whose mischief causes a very similar damage pattern. Fire blight, on the other hand, is a plant disease caused by the Erwinia amylovora bacterium, which occurs primarily in pome fruit plants. Even if the name suggests otherwise, the infected leaves and flowers wither and turn brown to black.

Is the pear grate notifiable?

A detected infection with pear grate is not notifiable. Since the infection is often confused with the actually reportable fire blight, a report is often made to the responsible horticultural authorities. Therefore, first check carefully which disease is actually involved. A comparison with the typical damage patterns will help you.