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Thursday, May 14, 2020

Twigs Dying in Ash

Q. Several years ago I purchased a Raywood Ash and I have been pruning off infected branches at the beginning of each season. Last week someone had a nursery suggested I apply a systemic containing imidacloprid and clothianidin as active ingredients to try to get some control. Do you know what the problem is?
Cicada damage to small limbs on sweet acacia

A. The problem you are seeing is most likely cicada damage from egg laying that is now healing. The female cuts a slit parallel along the top of the stem parallel to the branch with her ovipositor (egg laying machinery). The female deposits her flattened oval eggs, about an eighth of an inch long, stacked up against each other along that slit in a nice row.
Cicada (probably apache cicada) on the limb of a sweet acacia in late June

            If you look at the old twig damage closely, the slit looks like tiny teeth on a saw and that slit is healing nicely. When the eggs hatch a few weeks later, the babies fall to the ground and take into the soil where they feed on tree roots.
            The insecticide applied as a soil drench might work because it is systemic. Another option is to apply a soil insecticide drench intended for killing grubs in the soil or eliminating the cicadas on the tree as you see them and before they have a chance to cut a slit and lay their eggs.
            Continue to cut off the branches if you want if they are unsightly to you, but the tree will heal fast if it is kept healthy.

Small Black Critters Chewing Leaf Holes

Q. For the past three years these little black critters have chewed holes in the leaves of my Mexican Primrose. What are they and how can I get rid of them permanently? Since Mexican Primrose is not a food crop, I sprayed them with Ortho’s Home Defense, but that may not be the best solution.
BB sized holes in grape leaves from flea beetle feeding

A. Thanks for telling me the insecticide you used but legally you are not supposed to use an insecticide unless the label states it can be used for that purpose. The active ingredient of the insecticide might work on flea beetles but unless there is a given rate of application on the label, then the rate to apply is not known. The rate of application can mean the difference between control or no control.

Mexican Primrose and Flea Beetle Damage

            Mexican Primrose is notorious for flea beetle damage in the spring and sometimes fall months. Knowing which flea beetle is yours is the first step in getting permanent control. If you elect to go down this path, take five or six flea beetles in a vial of alcohol to the Nevada State Department of Agriculture and ask their entomologist in Reno to identify the type of flea beetle. Once the flea beetle is properly identified, methods of permanent control can be discussed. There is quite a bit of literature on permanent control without chemicals.
Flea beetles are quite small

As far as I am concerned, flea beetles are vagabonds and become a problem frequently during the spring, and sometimes fall months. Mark your calendar because they will come near the same date in the spring most years. This date signals you to start looking for them or their damage and apply the proper control measure.
Heavy flea beetle damage on grape leaves

            Flea beetles last about three weeks and they are gone. They can cause a lot of damage in a noticeably short time. If you see damage during the fall months, mark your calendar. Watch for holes in the leaves that signal their feeding has begun. They hide out on the bottom of leaves so you must spray “up” as well as over the top.

Pesticides and Controlling Flea Beetles

            Conventional insecticides used for controlling flea beetles include Sevin (active ingredient of carbaryl) or one of the pyrethrins (look for something ending in -thrin in the active ingredients). These must be applied each season you see them. Once damage is done, cut the plant back to get rid of the ugly parts, fertilize, water, and let it regrow.

Food Production - Is it Safe to Eat?

Farming in the Age of COVID-19

By Renee Pinel

Thanks to the COVID-19 pandemic, hand sanitizers and bleach wipes are now a part of our daily lives because everyone understands that we need access to chemicals that  kill the germs and viruses that can kill us.

Yet, as things drag on, more and more weary Californians are struggling to stick with shelter-in-place orders. People are venturing out more.  We don't see as many masks. Businesses are defying state guidelines.  People are starting to let down their guard.
This is likely a combination of factors.  One, it is human nature to want to be amongst others.  Two, people are making their own calculations on their risk of exposure, based on individual circumstances.  Three, it is just plain difficult for anyone to sustain intense self-discipline over a long period of time.

But we know it is possible to maintain strict standards of safety.  Look at California farmers.  For decades, they have possessed "safety-first" behaviors and practices now deeply ingrained in their DNA.  During the COVID-19 crisis, our farmers have continued to put food on the table and fill food banks while keeping their workers and communities safe.  They have achieved this not by adopting new standards of safety, but by continuing to follow existing requirements for pesticide use and safe food handling.

Californians may take this for granted.  But agriculture's emphasis on safety has been the result of a lot of work, dedication and collaboration between farmers, their communities and government.  Consider:
  • Farmers have been able to continue to produce food because health and safety rules are the norm - not the emergency exception.
  • California farmers have absolutely no interest in short cuts that compromise safety.  They and their families work on the farm. They value their workers. They live in the community. 
  • Our farmers operate under the most restrictive safety standards in the country, if not the world.  Long before COVID-19 became a household word, farmers and farm businesses were investing in the safety of their employees, communities and environment.
  • Scientists with the United State Environmental Protection Agency and California Department of Pesticide Regulation (DPR) conduct the most rigorous pesticide safety testing of anywhere else in the world - more than 300 safety reviews before a product may even be considered for use. 
  • It takes more than seven years to register a pesticide in California.
  • This is the same agency that regulates the sanitizers members of the public are comfortable using at levels that exceed the recommended amounts. 
  • Just as DPR reviews sanitizers designed to kill dangerous germs, they also review products used by farmers to kill dangerous pests.
  • Unlike the sanitizers that the public uses, DPR continues to regulate agricultural products after a purchase is made.  Farmers may only purchase and use an approved pesticide if they receive a "prescription" from state-licensed experts, who dictate terms of every use. 
  • Agriculture follows a complex system of permitting, monitoring, inspections, and reporting to assure that products are only used as labeled.
  • Farms provide personal protective equipment (PPE) and other safety protections to employees.
  • Farmers, farm workers and professional pesticide advisers receive continuous education on the safe use of products.
  • Farmers report all usage, and provide safety buffers around fields and additional precautionary buffers around sensitive sites like schools.
  • To assure all these rules are followed, Agricultural Commissioners and DPR inspectors enforce high standards on farms and other agricultural businesses.
  • These inspections cover the comprehensive array of federal, state, and local worker safety as well as environmental and community human health laws and regulations that cover the agricultural use of pesticide products.
During this pandemic, farmers have continued to maintain these high safety standards - even around schools, which are closed.  They have not asked for any current pesticide law or regulation to be suspended or relaxed.  Neither DPR nor the Agricultural Commissioners have suspended or loosened a single regulation during the COVID-19 pandemic.

Farmers continue to keep farmers markets, food banks, and grocery produce sections filled with healthy, fresh fruits and vegetables under the same strict standards as they always operate under.

While those of us in towns and cities continue to live under special emergency orders that at some point will be relaxed, we can be secure in the knowledge that farmers will continue to protect their employees, communities and the consumers of their produce - long after the Governor lifts his emergency orders. 

Sunday, May 10, 2020

Converting Peach Tree Irrigation from Twice a Day to Normal

Q. I have a well-established, prolific peach tree. About this time every year it loses some of it's immature fruit and I know that is normal. However, this year it's losing an abundance of fruit. I'm literally picking up 50-100 peaches a day. I have checked the irrigation and it seem to be fine with drippers at 15 minutes per day, twice a day.

A. This will be a challenge. Get ready for an irrigation overhaul! The usual reason for fruit drop is because the fruit was damaged in some way, either from a lack of water to the tree or cold temperatures that hurt the fruit. I don't think there were cold temperatures this late in the year, so I go back to the water issue.

Irrigation Twice a Day

I don’t like that you are applying water every day; twice a day in fact! Is there any way that can be changed to less often? That irrigation frequency sounds like watering a lawn or vegetable garden when its really hot and windy out! I don’t know about the amount you are applying, but you are applying water way too often.

Peach Tree Irrigation and Woodchips 

Fruit trees should have water applied to them twice a week right now and growing in most soils. The applied water should be enough so that the roots of the tree get wet to a depth of about 18 inches. For fruit trees growing in the desert, I like to see a layer of woodchips on the soil surface 3 to 4 inches deep. These woodchips provide a layer that protects the roots from getting too hot, conserves water, prevents most weeds from growing and helps keep the soil dark and rich.
This is an irrigation basin around a peach tree filling with water.

You are watering so often, unless you have very sandy soil, I imagine the tree roots  are growing about 2 inches deep. They should be growing 18 inches deep. Roots growing shallow like this are cycling back and forth between too dry, too hot or too wet. Roots can’t grow deeper because they are drowning (if you are watering a lot) or getting too hot and dry (if you aren’t watering enough).

Thirty minutes of water is meaningless to me. I need to know how many gallons you are applying and where it’s being applied.

What to do? 

This is tricky because the tree roots need encouragement to grow deeper and hot weather is already here. Root growth would be better starting in October when temperatures are cooler. Do not apply any more water using the current irrigation schedule of twice a day.
Free woodchips from local arborists who wanted a place to dump clean mulch.

Cover all the soil under the tree’s canopy with 3 to 4 inches of woodchips. Apply water to the soil 12 inches from the tree trunk all the way to the edge of the canopy. This can be done by constructing a donut around the tree trunk 6 to 8 feet in diameter.
Basin beneath grapes that didn't hold the water. It was repaired but easy to see!

The inside of this donut must be flat with a circular wall that is 3 to 4 inches tall. Fill the inside of this donut with a 1-inch layer of compost with woodchips on top. Fill the inside of this donut with water once a day. At the end of August, begin watering every other day. At the end of September water every third day. By December you should be watering once a week.
Rectangular basins with flat insides to hold water but let people and equipment through.

I generally figure that most peach trees that produce an abundance of fruit should only be allowed to keep about 1% or less of all the fruit produced by a tree. I'm assuming you are removing fruit that are closer than three or 4 inches apart all through the tree.

When peaches are pruned in the wintertime about half of all their branches are removed from the limbs. The removal of these branches are so that the remaining branches produces fewer fruit and there is less thinning to do. Otherwise there's a lot of limb breakage because of the weight of the peach fruit.

Bay Laurel or Carolina Cherry Laurel?

Q. I found your blog and am hoping you can tell me if this tree in the picture is a Bay Laurel. I have looked at pictures of Carolina Cherry trees that also look similar. This tree has supports which I know need to be removed at some point. The tree was planted by my builder in February of last year.

A. Looks like Bay Laurel to me. Bay Laurel is a Mediterranean tree and more tolerant of our desert climate than Carolina Cherry Laurel. Carolina Cherry Laurel is native to the southeastern US and not tolerant of desert conditions without proper site selection, soil preparation and watering.
            One easy way to tell the difference is to crush the leaves and smell the herbal (Bay) aroma of Bay Laurel. Bay Laurel leaves are pungent in their aroma. When you crush the leaves of Carolina Cherry Laurel they have an aroma of cherry rather than herbal. 
            The second way is to look for round “glands” at the base of the Carolina Cherry Laurel leaf where the leaf is attached to the petiole (leaf stem). These “glands” are characteristic of many plants in this genus (Prunus).