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Thursday, December 6, 2018

Pruning Plum and Pluot Is Similar

Most plums and pluots produce their fruit on short, compressed stems called spurs. Sometimes these spurs can be long and thin and other times short and stout and everything in between. The spurs don't always look the same.In foreign countries I have been confused more than once among the plums.

Please take a look at my fruit tree pruning classes each December and January in Las Vegas. Sign up for them at Eventbrite


These are fruiting spurs of one particular variety of plum. Don't prune these off unless you know what you're doing.
These are flowers opening on fruiting spurs of a particular type of pluot. Likewise, don't prune these off unless you know what you are doing. Once fruiting spurs are gone, that limb will never grow them back.

Pluots are made by humans that cross plums with apricots, hence the name pluot. Because they have more genetics that are from plums then apricots, the fruit looks more like plums. They range in color from green, to yellow, to orange, to red and dark purple.
This is a donut pluot that, I believe, was never released.

Open center versus modified central leader

Because they are so similar, producing their fruit on spurs, they are pruned similarly. They can be pruned either open center or as modified central leader. This structure of the tree is pruned the same as any other fruit tree with the same structure.Fruit trees that are more bushy are pruned as an open center.

Fruit trees that are more upright with a strong central leader are pruned as a modified central leader.But where the fruit is produced is a totally different matter and this is where pruning differs among fruit trees.

Videos released on My channel on YouTube

Watch these 2 videos that I made in the last few days that talk about pruning plums and pluots. I don't let these trees get more than about 10 feet tall through active pruning. This facilitates spraying if needed, pruning, management and harvesting. These trees are planted 10 feet apart in rows oriented north to south. They are irrigated with drip tubing and the soil is covered in woodchips, pruned from local trees.

Earthworm Castings (Vermicompost) Suppresses Insects and Disease

Q. I was reading your blog about worm castings, the chitinase enzyme produced by worms and its ability to control insects. Chitinase has been proven to degrade the chitin that holds insect skeletons together. Chitin is necessary for strong insect exoskeletons. So, using worm castings in garden soils will control insects.
Homemade worm castings from red wigglers in an earthworm bin.

A. Scientists think this may be true about worm castings are vermicompost, but the research hasn’t linked everything together yet. Chitinase occurs in the soil because of earthworms but does this chitinase control insects? Is the soil transferring this chitinase to the plants? Some preliminary research claims it can. The research is going on right now to find out how much value chitinase has controlling problem insects in the garden.

Insect pests controlled

           Studies report that Vermicompost application suppressed 20 – 40% pest problems arising from aphids, mealybugs, cabbage white caterpillars on pepper, cabbage and tomato.
            Gardens are filled with insects. There are good insects and there are bad insects. Can the effects from earthworms only kill the “bad bugs” or will it also kill the “good bugs”? This is why more research is needed.
            This is a similar problem with some of the “organic” insect control chemicals. Soap sprays and oils don’t differentiate between “good bugs” and “bad bugs”. They kill them both. We have to rely on our knowledge about “good bugs” and “bad bugs” and how it might be applied to control only the “bad guys”. 

Plant disease controlled

            There is some evidence worm castings or Vermicompost inhibited some fungal diseases as well as some nematodes in field trials with pepper, tomatoes, strawberries and grapes. It is believed the reason is microbial antagonism. The same effects have been found in manure and compost applications. Sterilizing both of Verma compost, manure and compost removed these effects.
             When only one plant disease was studied, the disease suppression was not as good when the Vermicompost was made from sewage sludge.

Wednesday, December 5, 2018

Push-Pull Method of Controlling Insects - Research

Note: It has been known for a long time that some plants attract some insects while others do not. An integrated approach to control insect pests has used "trap crops" as either early indicators that problems might occur or lure them away from more important crops. It is also well known that some crops repel insects while others do not. There is alot of information being circulated on the net. Some of it is true and others of it are not. Research can be used to confirm or deny it happens and identify what chemicals are responsible for this very important concept.

You might not recognize this beetle because it's so small and here it is pictured large. But if you have walked in the mountains among the pine trees and noticed that some of them are dying or dead, then you may know of Ambrosio Beetle damage. Brown ponderosa pine may show the BB sized holes in the bark and the galleries in the trunk produced under it.

Ambrosia beetle is more a problem in the tropics than in the temperate climates like the US and in particular the Mojave Desert but the push-pull concept is still interesting.

 Comparison of different methods to assess the seasonal and diurnal activity of ambrosia beetles (Coleoptera: Scolytinae)

  • Jason B Oliver, Christopher Ranger, Michael E Reding, Samuel Ochieng

  • Journal of Applied Entomology
    November 2018

    Non‐native ambrosia beetles (Coleoptera: Curculionidae), especially Xylosandrus compactus (Eichhoff), Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford), are destructive wood‐boring pests of trees in ornamental nurseries and tree fruit orchards. Previous studies have demonstrated the adults are repelled by verbenone and strongly attracted to ethanol. We tested a “push–pull” semiochemical strategy in Ohio, Virginia and Mississippi using verbenone emitters to “push” beetles away from vulnerable trees and ethanol lures to “pull” them into annihilative traps. Container‐grown trees were flood‐stressed to induce ambrosia beetle attacks and then deployed in the presence or absence of verbenone emitters and a perimeter of ethanol‐baited interception traps to achieve the following treatment combinations: (a) untreated control, (b) verbenone only, (c) ethanol only, and (d) verbenone plus ethanol. Verbenone and ethanol did not interact to reduce attacks on the flooded trees, nor did verbenone alone reduce attacks. The ethanol‐baited traps intercepted enough beetles to reduce attacks on trees deployed in Virginia and Mississippi in 2016, but not in 2017, or in Ohio in 2016. Xylosandrus germanus, X. crassiusculus and both Hypothenemus dissimilis Zimmermann and X. crassiusculus were among the predominant species collected in ethanol‐baited traps deployed in Ohio, Virginia and Mississippi, respectively. Xylosandrus germanus and X. crassiusculus were also the predominant species dissected from trees deployed in Ohio and Virginia, respectively. While the ethanol‐baited traps showed promise for helping to protect trees by intercepting ambrosia beetles, the repellent “push” component (i.e., verbenone) and attractant “pull” component (i.e., ethanol) will need to be further optimized in order to implement a “push–pull” semiochemical strategy.

    Take home lesson:  The push pull method of controlling damage from insects is an important concept in natural pest control but it has a ways to go before it can be easily implemented in integrated pest control.

    Oleander with Yellow Bug Infestation

    Q. I have oleanders in my backyard and noticed some yellow bugs on the flower stems. What are they and how do I get rid of them?

    A. These are highly specialized yellow aphids simply called “oleander aphids” because they have adapted to feed on the toxic plant juices of this plant. They might be poisonous themselves because they drink so much of the oleander fluids.
    Oleander aphid is not as common in the Mojave Desert as it is in wetter places like Florida or Louisiana. There are different aphids for different plants and they don't necessarily switch plants. There are some aphids that are general feeders and other aphids that have developed a tolerance for toxic plants juices like oleander. http://entnemdept.ufl.edu/creatures/orn/shrubs/oleander_aphid.htm

    Different strokes for different aphids

                Aphids can be red in color, green, brown, black and in your case yellow.  Some aphids are general feeders like the green peach aphid and can be found sucking plant juices on a variety of plants while most are very specific, like yours, only feeding on oleander.
                Control is the same for all aphids. The products with the least impact on human health are soaps and oils like Safer’s Insecticidal Soap and Neem Oil. 
    This is my picture of Neem Oil produced by Monterey. You might be interested to know that there are different qualities of Neem Oil out there. Some neem oil is coldpressed for extraction, some is hot pressed and some is extracted with chemicals.

    More information on neem oil

    The National Pesticide Information Center has developed an information sheet on Neem Oil you might find interesting to read.

    Other more potent and specific chemical controls are the general garden insecticides like pyrethrin products. These products last longer after you spray so they give long lasting control while the soaps and oils must be sprayed more often and only when the problem occurs.

    Moisture Meters and Rebar Tell You When to Water and How Much to Apply

    Q. Our water bill gets high in the summertime. I suspect we're overwatering but don’t know. What strategy can we go through to determine when plants are getting just enough water. More than enough is hard to determine.

    A. There are 2 pieces of information you need when irrigating: how many minutes to run the irrigation timer and how often. This is the basic information that's entered into an irrigation controller in a variety of methods. Irrigation controllers have all sorts of whistles and bells but that 2 pieces of information is what is needed.

    This requires a small investment on your part in the beginning. The two questions that need answering are when to water and how long (minutes) to water. 

    How often to water

    You will need some sort of moisture meter that measures soil moisture and a steel rod for determining how long to water.
    This is an inexpensive moisture meter you can buy for under $10 at any hardware store for nursery. They are made for use with houseplants and so they probably won't last very long when you try to push them in our soils. But they are fairly accurate. Most houseplants should be watered when the meter shows a "6". For houseplants use distilled or RO (reverse osmosis) water. 

    There are two types of soil moisture meters available. One is inexpensive you can buy at box stores for houseplants for less than $10. A better one can be bought online for $40 – $75, can be pushed into more difficult soil and lasts longer. I have purchased both the Reotemp and Lincoln soil moisture meters and the Lincoln lasted. The Reotemp fell apart after a few tries.

    This is the Lincoln soil moisture sensor and has had a solid workout for two years in tough Las Vegas soils.

    /The Reotemp soil moisture sensor broke after a few tries. The tip came off. Same problem was reported by another person to me. The tip was not secured to the sesnsor rod and it fell off.

    All of them have the same scale for moisture readings, 1 – 10. After calibration, recently watered soil will read 10 on this scale. Irrigate days later when the scale reads six. The expensive one lasts longer and can be used in more difficult soils, but it gives you about the same reading as the inexpensive one.

    How much to water

    How much water to apply or how many minutes on an irrigation controller requires a steel rod about three feet long. Use a 3/8-inch diameter steel rebar that is 3 feet long. They can be purchased at the major box stores for about one dollar. Shortly after the irrigation, push the steel rod into the wet soil in several spots.
    Image result for steel rebar home depot
    This is what the steel rebar looks like if you go looking for it in the store. You can get it at any box store/hardware store. Get the 3 eighths inch diameter rebar and select one that's about 3 feet long. They will have them in various lengths. If you want to get fancy you can sharpen the end of it into a point on a grinder and bend the top over into a handle. But using it as is works just fine. Pushing this into the wet soil will tell you how deep the water has penetrated. It slips into wet soil easily but when it hits the dry stuff it's hard to push. Lawns and flowerbeds should be irrigated to a depth of 8 to 12 inches. Large trees should be irrigated to a depth of about 2 feet. https://www.homedepot.com/p/1-2-in-x-20-ft-Rebar-REB-4-615G4-20/202532809

    Steel bars slide easily through wet soil until they hit dry soil. Trees and large shrubs should have wet soil down to at least 24 inches. 12 inches is usually enough for most other plants including lawns and vegetables.
                Water long enough, or apply enough gallons, to make the soil wet to the desired depth for all the plants on that circuit or valve. If some plants aren’t getting enough water while others are, add more emitters to those that aren’t.
                The first two seasons you might have to measure soil moisture and use the steel bar five or six times to get a “feel” for when to water. But after the second year you will start recognizing a seasonal pattern to irrigating plants in your landscape and you will not need them as often.

    I bought both the Lincoln and Reotemp moisture meters on Amazon. The rebar I bought at Home Depot.

    Bagging Apple Decreases Nutritional Quality of the Fruit

    Effect of bagging and time of harvest on fruit quality of 'Red Fuji' apple in high altitude area in China

    Baihong Chen, Juan Mao, Baona Huang, Baoqin Mi, Yulian Liu, Zijing Hu and Zonghuan Ma
    College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, 730070, PR China

    What is already known on this subject?
    The positive impact of bagging apple during its development on the appearance quality of the fruit has been extensively published.

    What are the new findings?
    Bagging 'Fuji' fruits during their development reduced the nutritional quality attributes measured.

    What is the expected impact on horticulture?
    Our findings provide a basis for strategies to improve the nutritional quality attributes of bagged 'Fuji' apples in order to maintain both the appearance and nutritional qualities.

    Introduction – The appearance quality of horticultural produce including fruits is a major factor influencing consumer acceptability. Two-year field experiments were conducted from May to September in 2013 and 2014 to determine the effect of bagging and number of days at harvest on apple fruit quality.

    Materials and methods – 'Red Fuji' (Malus domestica Borkh. 'Nagafu No. 2') apple was used. Two levels of bagging (i.e., bagged fruits and un-bagged fruits) and five levels of time of harvest including 170, 175, 180, 185 and 190 days after full bloom (DAFB) were studied in a randomized complete block design with three replications. The bags were applied at 35 days when most of the flowers were observed to have opened and then removed at 131 days after the bagging. The external and internal qualities of the fruits were assessed by physical and chemical analysis.

    Results and discussion – Bagging improved most of the appearance quality parameters including longitudinal and vertical lengths, skin color, cleanness and firmness of fruits. Spot sizes and spot densities decreased in bagged fruits. Soluble solids, soluble sugar, titratable acidity and vitamin C content were, however, high in the un-bagged fruits. The soluble solids and soluble sugar in both bagged and un-bagged fruits increased after 100 days storage. Titratable acidity in both bagged and un-bagged fruits, however, decreased after storage. Harvesting either 185 or 190 DAFB was more appropriate for maintaining the quality of both bagged and un-bagged fruits.

    Conclusion – In the high altitude area of China, bagging improved the appearance quality of the 'Red Fuji' apples. Better internal quality was, however, obtained from the un-bagged fruits. Harvesting 185 or 190 DAFB was most appropriate for improved quality of the apples in this area.