Pear Tree and Fireblight Disease

Q. I  attached pictures of my pear tree. Do you have any idea why the leaves are doing this strange browning and dying out? Never seen anything like this.

Both pictures were submitted by the reader. Sure looks like fireblight disease to me.

A. I'm going to state the obvious. The leaves turned brown because they are dead or dying. I know you want to know why they are dead.

The usual reasons can be wide-ranging and related to either diseases, damage to limbs or the trunk or soil problems. The possibility that concerns me the most is a disease called ‘fireblight’. Search the Internet or my blog for pictures of what fireblight disease looks like. Check the entire tree for this kind of damage.

Advanced stage of fireblight disease. The tree can still be saved by pruning back about 12 inches to stop the disease from spreading.

If you are at all suspicious of fireblight, then prune out these branches 6 to 8 inches below this area and use a sanitized pruning shears. If more than one cut is needed, then sanitize your pruning shears between each cut. Use 70% isopropyl alcohol or higher or a cigarette lighter and heat up the blades to kill any possible disease organisms that you could transfer to the cuts.

Make sure the tree was planted with compost mixed into the soil as an amendment at planting time. Never surround fruit trees with rocks or gravel on the surface of the soil. Woodchips that can decompose and benefit the soil are much preferred over rocks for any kind of fruit tree.

Fireblight disease on recently planted 'Bartlett' European pear.

If you are watering daily, the tree roots could be suffocating because the soil stays wet and not draining properly. Root suffocation can also cause the leaves to die and turn brown or black. Stop daily watering. Water every other day or every third day during the heat of the summer. Apply enough water when irrigating to cover a large enough area under the tree to initially wet and keep this soil from totally drying out until the next watering.

Pear trees grow very well in our climate if the soil is prepared at the time of planting with compost and if the soil surface is covered in woodchips after planting. You should never have to water daily if you are giving the trees enough water, over a large enough area, when you are watering.

Soil Testing for Home Gardens and Landscapes

 Testing the soil for home landscapes doesn't need to be done every year. They are expensive. Start with a baseline soil test (beginning) and test the soil every three to five years or when you think it is necessary. Many of these retail home soil tests can also be marketing tools for selling amendment products.

Home soil testing come in kits like La Motte's or a soil sample you can send in for analysis like the one below. Testing raised beds for gardening is no different than a small garden area without sidewalls. Make sure ALL the important plant nutrients have been tested in desert soils.

There has been a lot of negative endorsements in general info about home soil tests. But in my opinion they aren't too bad if you are looking for general numbers. 

This is an example of a home soil test result from Las Vegas, Nevada. It was not too bad. Not as precise as a commercial agricultural soil testing lab but not too bad.

Agricultural Labs

For more precision I would recommend a commercial agricultural soil testing laboratory that can invest  hundreds of thousands of dollars in important equipment. For research we use A and L Soil Testing Laboratory in Modesto, California, or do it ourselves but a good soil testing labs are considerably less expensive than doing it yourself for research. The major advantage of a lab doing it for a fee and home testing is usually the numbers of tests you can run. Home testing usually involves several tests for the same price while a commercial lab you only can submit one soil sample for a fee.

Use a Local Lab

It is important to submit samples to a lab that represents your type of soil. Some of the big labs need to know a bit about your soil sample before you begin. Soil testing can be different in different parts of the country. If you live in an arid/desert part of the country, submit it to an arid/desert soil testing laboratory.

This is an example of a commercial agricultural soil testing laboratory report. 

Commercial agricultural soil testing laboratories invest a considerable amount of money in testing equipment. They are expensive but when accuracy is needed they do a very good job. 

Examples of commercial agricultural soil testing laboratories in desert areas to consider include A and L in Modesto, and  IAS in Phoenix,

In some states an agricultural soil test is available from the University. These are a good bargain and give you valuable and accurate information.

What to Test?

Most soil testing includes nitrogen, phosphorus and potassium and a few other nutrients. Besides these, in desert soils make sure your soil is tested for iron, manganese and zinc as well. Don't forget the pH (alkalinity) and EC (salts) to include the salts of sodium, chlorides and boron. Boron is important for soil testing in desert soils.

Remember..."garbage in, garbage out." Always submit a good soil sample.

Planting During our Desert Heat

Leaf scorch can be a reminder that the plant might be in a hot location, soil not amended properly or it was not surrounded by wood chips when it should be.

 Avoid planting anything during our desert heat. All planting should stop if it's windy or temperatures are above 100°F. Sometimes you must plant but think about other times. They will be better and you will have more success. Planting during cooler weather is better for the plant. Planting during cooler weather and you will have more success.

If you must plant during the heat:

Plant in areas of the landscape appropriate for the plants. Some plants tolerate desert heat better than others. No plants like heat. They prefer growing at temperatures they like (45F to 85F depending on the plant).

Dig planting holes and amend the soil a day ahead. Fill the planting hole with water when you're finished.

Plant only during early morning hours.

Avoid planting on windy days. Check your phone weather app.

Have water ready and available. Would you like some coffee you like some coffee no?

Always plant in a "wet hole", never a "dry hole".

Plant as soon as you get home. Never wait for tomorrow.

Keep plants roots wet. Feeder roots in without moisture die within 15 seconds. How many roots die determines the degree of "transplant shock". Transplant shock isn't "normal".