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Saturday, April 28, 2018

Learn the "Browns" and "Greens" of Composting

Q. When composting, we are told to mix “browns” and “greens” together for a good balance of carbon from the “browns” and nitrogen from the “greens”. I am puzzled. All living things have both until they are composted. To me, the browns add fluffy aeration to the soil while the greens clump together in the compost pile. Is it possible that the mix of browns and greens is as much for texture as it is for carbons and nitrogen?

A. This is a huge question that requires a lot more space than this column permits. Compost is used as an amendment for soils for two reasons; because it can positively change the chemistry and structure of soil. I will try to answer it more completely in my blog.
Composts applied to soilsboth chemically and physically alter it.Most compost have an acid reaction and lower the soil pH. It adds nutrients to the soil. The type of nutrients it adds depends on what was used to make it. A wide variety of "brown" and "green" will give it a wide variety of nutrients. Composting with wood products that have been industrialized with chemicals such as fire retardants, paints, preservatives will end up in the compost made. Garbage in, garbage out.

            Browns and Greens

The terms “browns” and ‘greens” are a simplification for the average person to make it easier to choose the correct plant ingredients when making compost. Dry wood, or sawdust made from wood is about 50% carbon by weight. The amount of nitrogen in sawdust is about 400 - 500 times less than the carbon. So, the carbon to nitrogen ratio of sawdust is about 400 – 500 carbons for every single nitrogen (brown).
            A good compost should have only 40 carbons or less for every nitrogen or less. Extra nitrogen must be added to this sawdust from “green”. It just so happens that food waste (greens) has about 20 carbons for each nitrogen. This is about the same as coffee grounds, which happens to be “brown”. The “brown and green” rule doesn’t always work!
Some composts are very rich (less than 20 carbons to one nitrogen) while others are not. Those very rich composts can also be used as a source of fertilizer for plants. They can't be marked as a fertilizer because the fertilizer content is not the same with every batch of compost. There are fertilizer laws in every state in the US. To be called a fertilizer, the amount of nutrients in each sack or volume must be consistent.This is the reason composts cannot be called fertilizers.

           Using Fertilizers As a Greens Substitute

Another option is to add nitrogen to the carbon or "browns" with nitrogen fertilizer such as 21-0-0 or 46-0-0. A much smaller volume of fertilizer is needed than "greens". This may not sit very well with some people such as the "organic crowd". The plant doesn't care where the nitrogen comes from but there are potential contaminants in mineral fertilizer products. Ornamental trees and shrubs that constitute "green waste" may be sprayed with pesticides. Sometimes it is impossible to know.

            Animal Manure

           Many composts use farm animal manure, rich in nitrogen, in combination with wood or paper products rich in carbon. Farm animal manures can be as low as 12 carbons for each nitrogen. Human manure can be as low as 6 carbons for each nitrogen. On top of that, animal manures are easier to collect and transport for composting.
            When “browns” and “greens” are mixed together in the right proportion, voilĂ . The compost has the magical carbon to nitrogen ratio less than 40:1. I usually aim for a carbon to nitrogen ratio close to 20:1.

Best to Carbon to Nitrogen Ratio

            Finished compost with a ratio of carbons to nitrogen of 40 (C:N = 40) has a small amount of nitrogen to give to plants. Compost with C:N = 20 has much more nitrogen to provide and can act similar to a fertilizer when applied to the soil near plants. But carbon and nitrogen aren’t the only “fertilizers” supplied by compost. The composting process releases all the nutrients contained in the ingredients. What goes in, must come out.
            So much for the chemistry. Compost also changes the structure of a soil. It acts very similar to peat moss and coir, making it more “fluffy”, while providing many more nutrients to the plants.

I recommend the following:

•           Learn how to estimate the C:N ratios and use it as a guideline about how much nitrogen to add to a compost
•           Use a variety of feedstocks for composting since plants have a range of nutrients locked inside them
•           Garbage in, garbage out. You cant make quality compost by adding feedstocks loaded with contaminants.
•           I don’t agree about not composting animal carcasses or animal by-products. It can be done. On farm composting of dead animals is a common practice. But it must be done correctly.

Leaf Yellowing of Pomegranate Could Be Weed Killer

Q. Eleven of my 50 young pomegranates have leaves yellowing and dropping off. I water this area once a week by flooding. I sprayed a weed killer, 2,4-D, near the pomegranates but I protected each one with plastic to avoid damaging the trees. Where did I go wrong here? If the weed killer is the problem, is there any way to save them?
It looks like the pomegranates were planted in a depression. The more I look at these pictures the more I'm concerned that it the roots may be kept too wet. The only way to know for sure is to use the soil moisture meter and measured the soil moisture just before the next irrigation. Generally speaking, pomegranates and most long grasses are not compatible. Another possible option is to plant pomegranates on a raised area of soil rather than a depression.
Even though the soil is cracked on the surface it tells you nothing about how dry it is only a couple of inches below the surface. Many weed killers can travel with water. Make sure no water is added to these plants within 24 hours after we killers are sprayed on the soil.

A. When I first saw your pictures I thought the soil was too wet. But I read your email that they were watered only once a week. Watering once a week in mid spring should pose no problem if the soil is not a heavy clay. If the soil is a heavy clay and remains wet a couple of days, this could cause leaf yellowing and dropping.
            In the picture, I saw grass growing close to the pomegranates. If watering only once each week, I assume the grass is Bermudagrass. Tall fescue should need watering more often than this. Grass growing close to these trees will cause them to grow more slowly. Particularly Bermudagrass. So it’s always a good idea to remove grass at least 3 feet from a fruit tree.
            The leaf yellowing could also come from a lack of nitrogen in the soil. However, if you are fertilizing that grass there is probably plenty of this fertilizer escaping to the pomegranates. Removing grass 3 feet from the tree will reduce competition for any fertilizers applied.
            Now on to the most likely problem; weed killers. It helped that you covered each of the trees with plastic before spraying. It’s even more important if you spray this kind of weed killer when temperatures are cool and there is absolutely no wind. Hot soil surfaces cause dandelion killers like 2,4-D to volatilize (turn into a vapor) and move very easily with the very slightest air movement.
This is 2,4-D damage, dandelion killer, on tomato. If the tomato plant is growing, the growth will become deformed.
            Damage from 2,4-D is easy to identify when the plant is growing and producing new leaves; new leaves are deformed. If the plant is not growing and producing new leaves, leaves turn yellow and drop. The branches that supported them may or may not die as well. All you can do is wait and see what happens.
This is weedkiller damage on grape. The weedkiller is unknown but the damage is unmistakable.
            I am concerned with the plastic. Make sure that the same side of the plastic using contact with the plants and that you don’t accidentally wrap the plant the wrong way.
            I think a better weed killer to use for your purpose might be Roundup. It does not volatilize as easily as 2,4-D. For it to work, the spray must land on green leaves or green limbs. If you prune pomegranates so their lowest foliage is about knee height from the ground, it will be less likely to be damaged.
            Keeping grass 3 feet from the trunk will also help. A small plastic bucket with a hole drilled in the center of the bottom, attached to a spray wand, will help contain the spray and directed toward the weeds.

Monday, April 23, 2018

My Husband Cut Down a Climbing Cactus!

Q. Look what my husband did? He cut my saguaro below the seams before consulting with me.  I know it looked kind of sick (the tree, not my husband), but he cut it. I am going to cut those chunks all the way down. 
Cuts on climbing cactus like these may look bad but they are repairable

A. From your pictures, I don’t think your cactus is a saguaro. I think it is one of the columnar cacti, also called a climbing cactus. Well, it is a setback for the plant because the cuts make it look ugly. The plant doesn’t care, but it is not pleasing to look at.

New growth from just below the cut

            If I’m right, and this is a climbing cactus, those cuts create new growth coming from the ribs just below the cut. The cuts will force new side growth, columns, that continue growing upward.

Propagating columnar cactus

            Another option is to remove all the damaged stems to a couple inches of the ground. Let them “sucker” and regrow below the cut. Remove damaged “arms” entirely if it looks bad. Cut these removed columns or “arms” into 12 inches long segments for planting. Put them in the shade for one to two weeks to heal the cuts before planting.
            After two weeks, plant them in soil amended with compost (not upside down!) with about one third of the 12 inches stuck in the ground. Stake to hold them upright until they grow roots and they don’t fall over. Water every 2 to 3 weeks so that the soil is dry between irrigations.
            Let the columns which weren’t cut continue to grow but “lean” against something upright. These cacti will get tall if they don’t freeze back during a very cold winter.
Many of the columnar cacti are also called climbing cacti. They get so tall they can fall over if they don't lean on something. Many of these cacti do not handle intense sunlight very well in the desert. In response to sunburn to the columns, these cacti will grow new site shoots and propagate themselves.
            In your picture, some columns appeared to be damaged by intense sunlight. This damage was forcing a lot of new side growth from the columns. This cactus will grow much better with amended soil and put in a location where it gets some shade from the late afternoon sun. Now might be a good time to move it to a new location and let it “lean”.

How to Control Scale Insects on Texas Mountain Laurel

Q. I planted a Sephora secundiflora in my backyard about 17 years ago. Today, I noticed many of the stems are infested with an insect that looks like a type of scale to me. The stems and leaves below the infested stems look wet and sticky.  The pavers underneath the plant are also wet and sticky. 
Those small red bumps on the branches of Texas Mountain Laurel, Sophora secundiflora, are insects

A. Your picture helped tremendously. 

Those red bumps are scale insects

Yes, you are correct. These brown, round bumps on the stems are scale insects. I have never seen these on Sophora, Texas Mount Laurel, before and I could find no reports of scale insects on this tree from anywhere. Scale insects provide a food for ant colonies, as do aphids. It’s mostly sugar from plant sap. That’s the sticky wetness you are seeing. Ants have a vested interest in protecting and colonizing ant and scale populations because of this sugary, sticky wetness.
Horticultural oils are pesticides made, typically, from a refined mineral oil.
            The most effective control of scale insects are repeat stem sprays of horticultural oils. These sprays should be applied several times during the cooler times of the growing season. Combine this spray with ant control in the same area.
Aphids and ants on apricot in Tajikistan
            Ants move scale insects around, much like they do aphids, to different plant parts and even different plants. They contribute to the spread of scale insects in trees and shrubs and can turn a minor problem into a major problem in a couple of months.
Some Amdro products are ant baits and can be used to kill an ant colony that is spreading and protecting insects producing sugary exudates like scale, aphids and others.

Controlling ants

            When controlling ants, use a poison bait in locations where there are problems. If there are no problems, no control treatment is necessary. Ants play a positive role in protecting plants from other insects.
            An insecticide called Amdro, an ant bait, has been effective in controlling the spread of aphids by controlling ant colonies. I see no reason why this treatment would not also control the spread of scale insects. You can find Amdro ant bait at any garden center or nursery.
            Most of our ants live in the ground in colonies. Identify the soil opening or openings to these ant colonies and spread 15 or 20 granules on top of an ant mound. Ants take this poisonous bait into the underground nest where it kills the entire population in 24 to 48 hours. The area where it’s applied must stay dry for 24 to 48 hours to work. Make sure the label of this product fits the needs at your site before applying it.

When to spray horticultural oil

            Horticultural oils are sprayed over the entire tree, top to bottom, if temperatures are below 90° F and no flowers are present. Repeating this spray three or four times during the growing season provides nearly 100% control of scale insects.

Follow-up with soap and water sprays

            Apply soap and water sprays to the tree 7 to 10 days after the horticultural oil application. Soap and water sprays kill any young nymphs that eluded the oil application. Remember, soap and water sprays, just like oil applications kill all insects sprayed, good or bad. Direct soap and water and oil sprays only to locations where there are problems. 

Cause of Dieback in Newly Planted Peach or Apricot

Q. Dying leaves on peach or apricot?

These fruit trees recently planted, whitewashed and the tops cut off. New growth occurred below the cut but it proceeded to die.

A. Not much information to go on with this question so I will give a broad response. From batch breaks pictures sent with this message, the fruit trees appear to be newly planted, whitewashed and the central stem pruned at about waist height.

Bareroot trees must be handled carefully

            If this tree was newly planted and bareroot (no container), it must be staked firmly in place, so roots do not move during the first few months of growth. Securing the tree solidly, in one place, encourages strong, future rooting.
            I assume the soil was amended with compost at the time of planting for better rooting and drainage. Build a donut or moat around the tree, 2 to 3 feet in diameter, to contain water from a hose. Water the tree with a hose once a day for three days in a row to settle the soil around the roots and remove air pockets.

How to water

            When that is finished, water every other day during warm times of the year. Make sure to skip at least one day before watering so that roots can "breathe". Watering every day for a month could suffocate roots and kill the tree or at least cause it to be sickly.
            Bareroot tree roots dry and die quickly. These important roots provide water and nutrients from the soil and are very small. Not large. These tiny roots dry out and die in seconds. Excessive drying of these roots causes “transplant shock” resulting in slow growth after planting.

Protect the tiniest of roots from drying out

            Bareroot trees can be finicky. You don’t see bareroot trees sold much anymore to homeowners. Only experienced gardeners should buy them. The roots of these trees must be kept moist from the time they leave the nursery until they are planted.

How to identify overly dried roots
The feeder roots of plants, responsible for the majority of water and nutrient uptake by plants, is even smaller than these small white roots of Myers lemon growing in a container.

            A common symptom of bareroot trees that have excessively dry roots is a short, flush of new growth after planting followed by their death. The death of new growth looks like a lack of water. And in reality, it is. Roots have died and can no longer supply water to new growth.
            If you think this might be the case, wait and see what happens after planting. In about two months, if you do not see new growth then the tree is dead and should be replaced.

Don't Move Plants in Late Spring!

Q. My dwarf Genoa lemon tree growing in a 12-inch diameter planter will be two years old in October. I'd like to plant it in the ground. Is this a good idea now? 

Eureka lemon growing in Las Vegas. One of the true lemons.

A. It’s a good idea to plant it in the ground but no, not now. Late spring is the absolute worst time to move fruit trees to a new location. Hot weather is coming quickly. Wait until mid to the end of September when weather cools a bit from hot, summer temperatures.
            Fall is the best time for planting and replanting, bar none. Spring is in second place but that’s when most plants are available.
            Take as much of the roots as possible in the move. Dig the new hole and have soil amendments mixed into this soil. Use this soil mixture for backfilling around the roots after it’s planted.
            Plant it as soon after digging as possible. Make a moat around the tree to hold water from a hose. Water it thoroughly with a hose three times in three consecutive days. Remove the moat and turn it over to your automatic watering system.

By the way, Genoa lemon looks very similar to Eureka lemon. It has never been that popular in the US but it is supposed to be more tolerant of cold winters than Eureka or Lisbon lemon but not Myers (which is not a true lemon).