Dealing with Bitter Rot Pear Disease
Karen is wondering what can be done to stop the problem of Deformed Rotting Bartlett Pears growing on her daughter’s beautiful tree.
Here’s what she wrote:
“Daughter has a bartlet pear tree that reaped abundant HUGE fruit this year which was, unfortunately, deformed with indentations and balck ‘holes’ . . .don’t know what the problem is and don’t know if spraying for a ‘fungus’ is appropriate. ???? Please enlighten us. Hate to see all this beautiful fruit going to the hornets.”
So here’s the steps I would take to deal with this situation:
Step 1.
The first step is to identify the problem by researching it online and in my gardening books. The question is,” Is this caused by a fungus or an insect?”
Since Karen said nothing about leaves or branches being attacked or infected, I presumed only the fruit had been affected. I could eliminate any problems which involved more than the fruit.
When I was researching the material, I came across a comprehensive pdf presented by the West Virginia University at http://www.wvu.edu/~agexten/ipm/insects/pcerti17.pdf, where all the diseases/problems re fruit trees were explained in detail.
The only pear pest I found that involved only the fuit was called “bitter rot”. According to the University’s information, bitter rot is usually found on the fruit only. It is caused by a fungus that can get through the unbroken skin of the fruit.
The article presented by the University continued to explain that “at midsummer or later, one can notice one or many small, light-brown, circular spot(s) on the fruit. If it’s quite hot, these spots enlarge quite quickly and soon change to a dark brown color. As they gradually reach 1/8 to 1/4 inch in diameter, the area becomes sunken in or shaped like a saucer. When the spots reach 1/2 inch one can see small black dots in the sunken area. As the fruit ripens, it decays rapidly and finally shrivels into a mummy.”
Disease Cycle –
The mummified fruit with the fungus still alive in it ends up on the ground while fungus spores, spread by wind and/or rain, end up in cracks and crevices in the bark or in the jagged ends of broken limbs. The fungus produces more spores which eventually are washed by rain unto the fruit. Then the cycle continues.
Ideal conditions for the bacteria to grow and multiply is humidity between 80% to 100% (lots of rain) and a temperature of 85 F or higher.”
Step 2:
The next very important step is to clean up all the leaves, dead wood/debris under and around the trees and send all to the garbage or burn it. These should never be placed in the backyard compost bin.
Step 3.
Once that is done, I would check the soil’s pH and soil type. In order for the tree to stay healthy, it must be able to absorb nutrition from the soil. That’s pH between 5.5 and 7 and rich loamy soil that drains well..
For further instructions on how to check the soil’s pH, you might want to go to http://plantsandgardeningtips.com and read the article “Testing Your Soil” found under the category “Backyard Gardening”.
The soil under the pear tree should have a pH between 5.5 and 7. The article will tell you what to do if it isn’t.
To find out how to check whether you have loam or something else as soil, read “Texture of soils“ which is found at http://organicvegetablegardeningguide.com/blog/texture-of-soils/
In that article, you will also find a video which will help you even more.
If the soil is clay or sand, it must be remedied. However, no matter the type of soil you have, if you want loamy soil, simply keep adding compost which will provide the tree with nutrition. If you don’t have compost, as a second choice one could work in manure in the soil around the tree base. A third choice is to use those “fruit stakes” found in the spring at gardening stores/nurseries and pound them in the soil under the tree. . . definitely not as good as compost or manure.
(Note: if you get manure from a farmer the manure must be at least one year old manure i.e. aged manure. Otherwise it’s safer to buy the manure at a nursery.)
Therefore, I would add plenty of compost around the perimeter of the tree, but this compost should barely touch the trunk of the tree. The bulk of the composted material (or wood mulsh, but not the colored stuff) would be spread from the trunk outward towards and under the tree’s drip line.
Step 4.
Early in the spring before the buds come out and after the weather stays above the freezing point , I would spray the pear tree . . . every crevice, nook, and cranny on the trunk and branches with horticultural oil.
For more information on how to do that, please check the article “Natural and Organic Fruit Tree Sprays” at my blog
http://organicvegetablegardeningguide.com/blog/
I just found out that there is a brand new organic horticultural oil made with Himalayan Cedarwood oil. This is just new, but I know that cedar oil is wood base oil and has been around for a long time.
This RX Horticultural Oil is being advertised as being enhanced by the powerful insecticidal and anti-fungal properties of Cedar Oil, great for eliminating stubborn insects and disease. The best part is that it is safe around people and pets.
So anyone living in Florida might find this product at a local nursery. However, you can read more about it (or buy it online) at http://www.greenthumbsremedy.com/Greenthumbs_Remedy/Premium_Horticultural_Oil.html .
Regardless, the tree must be sprayed with at least horticultural oil and maybe with what nurseries call “dormant spray,” a mixture of sulfur and oil (although I personally would try oil only because I hate working with the sulfur mixture)
Step 5
After this initial spraying with the oil, I would continue with a spraying program. I would spray the tree every 15 days (or more often if it rains) with the home made recipe which can be found outlined in the article “Natural Sprays for Fruit Trees” (on this blog).
I have used this recipe over and over as a prevention program on all my fruit trees . . . one of them being a pear tree. The trees love it, especially when I added the molasses (an antifungus ingredient). A second ingredient which helps get rid of fungus is the garlic.
This recipe can be used all summer long as often as you wish for it’s made up of ingredients found in your cupboard. Just be sure to spray EARLY IN THE MORNING when there’s no wind and before the sun gets hot.
Having said all this, I strongly encourage Karen to get a second or even a third opinion from nursery owners who may have seen these conditions ruining the pear fruit on trees in her area. All I’ve done here is explain how I would deal with the situation. There are many factors which are missing; therefore, I cannot be absolutely certain that I have pegged the correct “disease”.
However, no matter the fungus or the insect causing this problem, you will have to spray to get rid of it. Remember it’s better to prevent than to cure, especially if you can use eco-friendly products.
Karen, if you read this, I would love some feed back regarding your tree. I hope I wasn’t too late with my response.
Good luck!
Marcie
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May 11th, 2010 22:23
I have attached a valid link for the cedar oil-enhanced horticultural oil discussed in this article.