Unfortunately, pathogens associated with this plant, when not treated promptly, can cause serious damage to your pear garden after a few days of spreading.
For those growing pear for the first time, understanding the origin of disease through the countless adverse changes in pear tree leaf blades can cause a persistent headache.
That’s why we’re here! This article is honored to provide you with all the pear tree leaf disease identification that can cause damage to your crop and the most effective pest treatment methods.
What Is Pear Tree Disease?
Whether you own a commercial farm or a pear tree in the garden, annual leaf diseases on pear trees can strike anytime.
They do not appear simultaneously but tend to occur in sequence, depending on the weather and the growth rate of the pear tree.
The time when pear trees are most susceptible to disease is from the time they enter the dormant stage until the fruit is harvested.
A seasonal disease management program is necessary for any pear tree to increase resistance and the percentage of healthy fruit.
In particular, you need to prevent disease when weather conditions are unfavorable, including abundant rain/cloud cover, high temperatures, and high humidity.
Pear Tree Leaf Disease Identification
In general, pests and pear leaf diseases often appear seasonally, with many different signs, and gradually increase in severity when the weather favors them.
Never ignore any suspicious changes on the green leaves of a pear, as they are the key to identifying the source of the disease that is raging on your farm.
Pear Tree Midge
Pear tree midge begins when the green leaf edges turn pink and then curl shyly. After a while, the cocoons become ugly black, containing many white pear fly eggs.
If you still have doubts about this disease, try cutting the young fruits growing around to look for small maggots inside.
These fruits often initially grow stronger than other fruits but will rot and fall after only a short time. Fortunately, this disease only affects single trees and does not affect neighboring trees.
The fungus Galeodes pomigena causes shiny black spots that gradually spread on the surface of both leaves and pears.
It grows especially strongly in early summer when the cloudy weather begins to rain heavily, air circulation is poor, and air humidity reaches its highest level.
Pears are only infected on the skin, so they can be cleaned by rubbing or rinsing thoroughly.
In addition, regularly pruning branches and leaves and trimming grass around trees promotes air circulation, limiting the risk of sooty blotch in the pear garden.
Pear scab caused by the fungus Venturia Pirina has similar symptoms to apple scab, causing velvety round spots.
They leave olive-black streaks on leaves, fruits, and branches before gradually turning gray and cracking.
The fungus can survive on fallen leaves, produce primary spores in the spring and secondary spores in the summer, and continue infecting the pathogen through the rainy season.
This disease will continue to rage from when the pear fruit begins until the end of June. During this sensitive period, any pear garden needs spraying with fungicide and removing all diseased branches.
Erwinia Amylovora bacteria are the leading cause of leaf blight, one of the most devastating threats to pear trees near harvest.
It grows at an extremely destructive level, able to destroy an entire pear garden in just a few months. Luckily, the disease spreads slowly, is easily isolated, and is not a fixed problem yearly.
Over winter, bacteria residing in old cankers on leaves and stems begin to develop through four steps: leaf blight, flower blight, bud blight, and traumatic blight.
As spring weather starts to warm again, bacteria multiply rapidly and ooze out of tissues as a creamy bacterial fluid. They attract insects or rely on the wind to infect the next victims.
The tissues of infected holiday trees are often black and cracked as if they had just been burned.
For diseased branches, it is best to prune 8-12 inches away from the source of the disease, then use bleach to disinfect all tools.
You may not believe it, but tiny aphids can also cause significant damage to your pear tree. They attack the underside of leaf blades, causing the leaf edges to roll inward (similar to midge disease).
After a period without treatment, the leaf edges gradually turn brown, rough yellow-brown spots, and small circular holes appear. Any leaf attacked by aphids is deformed and cannot develop normally.
Pear Slug Sawfly (Caliroa Cerasi)
Pear slugs (Caliroa cerasi) cause considerable damage to fruit trees and ornamental shrubs, such as hawthorns, apples, cherries, and pears.
This creature looks like a black sponge – its green body is covered with black slime to protect it from predatory birds.
Pear Slug Sawflies spend the winter pupating in the soil under trees, similar to cicadas. In spring, they begin to attack and lay eggs on the top of the leaves.
After about 3 to 4 weeks of infestation, the larvae will fall to the ground to wait for a second attack around late August to mid-September.
Although this pest can damage large amounts of leaves, it is unlikely to cause tree mortality and affects fruit (as damage only occurs later in the year).
\However, it causes a loss of aesthetics and hinders the photosynthesis process of weak pear trees.
You can remove them by hand or spray them with strong water to dislodge these pests from the foliage.
Pesticide products (such as Bifenthrin) can also provide extremely effective and quick slug-killing results.
Pear Leaf Blister Mites
Pear leaf blister mites cause small, colorful (red, pink, or green) blisters on the leaf surface. Over time, the blisters become darker and gradually turn dark brown or black.
Once signs of blister mites are detected, destroying the fly larvae inside seems impossible. Fortunately, they only affect the plant’s leaves rather than fruit production.
Spraying plant chemicals in winter (November-December), especially in bud joints and young shoots, effectively helps limit damage next year.
Spend a few days trimming as many damaged leaves as possible to limit the number of new mites. As the weather in March gets drier, ensure your pear tree always gets plenty of water.
Any pear grower can easily detect Pear Rust through blisters on the underside of the leaves combined with orange spots on the top of the leaves.
In the fall, infected spores will spread through the air to parasitize another plant, including a bush or juniper.
When winter ends, these spores are released again around May-June and return to pear leaf blades within half a mile.
Unfortunately, there are no chemical products that can completely treat this infection. You can only prune diseased leaves, spray preventive medicine, and keep the tree healthy enough to resist Pear Rust attacks.
Fabraea Leaf Spot (Leaf Blight Or Black Spot)
Fabraea leaf spot disease caused by the fungus Fabraea maculata usually appears at the end of the pear growing season or around May-June.
It attacks branches, leaves, and pears with ugly brown-black spots. Severely diseased leaves quickly turn yellow and fall, affecting the garden’s vitality.
The black spots on the fruit’s surface quickly sink and necrosis, then crack. Fabraea maculata fungus overwinters in huge numbers on infected leaves, making it extremely difficult to control.
When spring comes, the spring wind will promote the fungal spores to spread to the next victims.
It would help if you started by removing infected leaves over winter, as they are the main source of fungal spores. Besides, spraying fungicides at sensitive times can control the risk of fungal attacks.
How To Control The Pear Tree Leaf Diseases?
Controlling pear tree disease outbreaks on pear leaves is a long battle requiring much time and effort.
In addition to choosing pear varieties with good genetic disease resistance, you need to strictly follow the disease control process to control and gradually eliminate dangerous pathogens from your orchard promptly.
To increase air circulation, you need to regularly prune the branches and leaves of pears, even while the tree is growing healthily.
Removing parts affected by pests and pathogenic fungi means eliminating sources of disease spread reducing pressure on the tree’s fruit production process.
Choose The Suitable Pesticides
Some common fungicides and pest control products you may consider include:
- Mancozeb: special treatment for Fabraea leaf spot and pear leaf scab.
- Ferbam: can be used alone or in combination with Thiophanate Methyl to treat Fabraea leaf spot, leaf scab, or black spot disease.
- Thiophanate Methyl: more effective when combined with mancozeb or ferbam to treat black spots, leaf scabs, and Fabraea leaf spots.
Whichever fungicide solution you choose, use the correct dosage and spray at the recommended intervals printed on the packaging.
Follow The regulated Spray Schedule
Refer to the table below to clearly understand the time of disease outbreaks on pear leaves at each stage of development of this tree species:
|Pear’s growth stage||Common disease||Recommended solution|
|Dormant||Fire blight||Prune diseased crunches|
|Green cluster bud||Fabraea and Scab leaf spot||Thiophanate Methyl and Mancozeb; only Mancozeb|
|First-cover||Fabraea, fire blight, and Scab leaf spot||Thiophanate Methyl and Mancozeb; only Mancozeb|
|Summer cover sprays||Fabraea, sooty blotch, and Scab leaf spot||Thiophanate Methyl and Mancozeb/ Ferbam|
Some Last Words
Pear trees are vulnerable to seasonal disease attacks, leading to damage and rot of tree trunk parts, typically the leaves.
Therefore, mastering the pear tree leaf disease identification can help you quickly identify the cause of the disease and take the most effective disease control measures.
After each campaign ends, always provide enough water for pears, prune branches regularly, and spray fungicides on time.
That is the key to protecting your perennial pear garden from affecting productivity and fruit quality. Good luck!