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Monday, May 2, 2011

Wind, Not Insects, Causing Damage to Tender New Growth

Wind Damage to Persimmon
Q. I hope you can help with a small problem with our dwarf peach tree.  Something is shredding the leaves and I cannot see anything after a close inspection.  Could this be a nocturnal pest?


Root Weevil Damage
A. We have a lot of wind damage right now and that does shred leaves. The only other nocturnal insect might be root weevils which I have never seen on peach but “notches” the edge of the leaf, not shreds it. My best guess would be wind damage and not to worry about it. If you sent me a picture of the leaf I could tell better. You will be able to see the difference on my blogspot, Xtremehorticulture of the Desert, or my weekly newsletter.

Yucca Damage May Be Preventable With TLC


Damaged Yucca
Q. Any thoughts on what is going on with these plants? I think it is over watering and would like to know how much water and how often it should be watered in the summer and winter. They are on drip. Thanks.

A. The problem is that overwatering and underwatering and some other problems can have the same physical appearance. I would tend to agree with you that it is a watering problem most likely or a drainage problem where the water cannot freely drain from the roots.  I do not think it is an insect or disease pest problem.

These look like maybe either Spanish dagger, Spanish bayonette or recurved yucca. It is hard to tell from the picture. The leaves are heavily damaged with dieback and discoloration. I will post it on my blogspot because I have had others send to me similar pictures.
Yuccas can have some variability on where it is best suited for planting depending on the species. In some yucca they must be watered more often or put into less stressful locations than others. Some are more cold hardy than others. It is a bit hard to generalize unless we know which yucca it might be.
Closeup of Damaged Yucca
Bottom line, these should be watered deeply, not with trickles of water from an emitter. So about ten to 15 gallons each time you water. Then, depending on the species it might be as often as once a week in midsummer.

This is possible it might be a location problem depending on the yucca. If this is a hot spot in the yard with lots of reflected heat and light this might be a microclimate problem. Some of the yuccas are native to the Southeastern US and may be a bit sensitive to our soils and climate or microclimate if not protected. Don’t assume they are necessarily all desert plants and can be treated like many cacti native to the desert. They aren't.

I don’t like it that it appears to be growing in rock mulch. It might be all right but its tolerance to heat and dryness will be affected by the soil conditions as well. They are always a bit better off and more tolerant to stress if the soil is at least somewhat enriched. Even cacti like an improved soil and perform better!

Sunday, May 1, 2011

Cool Spring Weather = Fruit With Less Sugar

Earlitreat Peaches
We are just about one week off from picking Earlitreat peaches, the first tree fruit to be harvested at The Orchard. Right on its heels are the apricots. The temperatures this time of year are very close to the temperatures we had last Spring; cool.


Cool weather does not tend to develop the sweetness and flavors that hotter weather does in many of our early fruit. Cool weather may also affect how the pit of stone fruit develops. Sugar content will be low unless temperatures start to rise consistently into the 90's. Total acidity and other flavor factors are also affected. The high temperatures of our desert usually cause our fruits to have very high sugar contents. The salinity of our soils may also increase sugar contents.
Refractometer
Sweetness can be measured in fruit and vegetables with a refractometer. This sugar content is usually measured in Brix. This indexes the sugar content (along with other dissolved solids) of the fruit through the refraction of light (the bending of light as it travels through plant juices; the higher the sugar content the more bending of light that occurs). This refraction of light is measured on a scale that can be seen through the adjustable eyepiece of the refractometer (upper right). The Brix scale is calibrated so that each degree Brix represents a 1% increase, by weight of, sucrose in pure water at 25° Celsius.

Refractometers can be purchased from several vendors such as Orchard Valley Supply, Spectrum Technologies, and other online sources.



A few drops of juice are squeezed from the food that you are testing using a garlic press and placed on the prism of the refractometer on the bottom left. If you have a handheld refractometer like the one above you look through the eyepiece and determine the Brix reading. If you have a digital refractometer, you calibrate the refractometer using distilled water, and press a button to have it analyze the sample and determine the Brix reading. Be sure to clean the prism each time a Brix reading is made.

Commercially, farmers can receive more money for what they produce if they exceed the sugar content specified in a contract for the products they produce. However when we "tree ripen" fruit we can consistently get higher sugar contents easily exceeding the "excellent" mark set in Brix tables. For instance apples suitable for the desert can achieve Brix readings over 20. Knowledgable growers will let the consumer know this content to add value to the product being produced.

     REFRACTIVE INDEX OF CROP JUICES
    CALIBRATED IN % SUCROSE OR °BRIX

Fruit
Poor
Exc.
Veggies
Poor
Exc.
Apples
6
18
Asparagus
2
8
Avocados
4
10
Beets
2
12
Bananas
8
14
Broccoli
6
12
Cantaloupe
8
16
Cabbage
6
12
Casaba
8
14
Carrots
4
18
Cherries
6
16
Cauliflower
4
10
Coconut
8
14
Celery
4
12
Grapes
8
24
Corn Stalks
4
20
Grapefruit
6
18
Corn, Sweet
6
24
Honeydew
8
14
Cow Peas
4
12
Kumquat
4
10
Endive
4
10
Lemons
4
12
Escarole
4
10
Limes
4
12
Green Beans
4
10
Mangos
4
14
Kohlrabi
6
12
Oranges
6
20
Lettuce
4
10
Papayas
6
22
Onions
4
10
Peaches
6
18
Parsley
4
10
Pears
6
14
Peanuts
4
10
Pineapple
12
22
Peas, Eng.
8
14
Raisins
60
80
Peas, Field
4
12
Rasp.
6
14
Peppers, Bell
4
12
Strawb.
6
16
Peppers, Hot
4
10
Tomatoes
4
12
Potatoes, Ir.
3
7
Waterm.
8
16
Potatoes, Red
3
7



Potatoes, Sw.
6
14
GRASSES


Rutabagas
4
12
Alfalfa
4
22
Squash
6
14
Grains
6
18
Turnips
4
10