Aphids Overwinter near the Soil on Many Plants

Q. I have a small crape myrtle tree with leaves that were constantly wet this year. The ground and plants underneath were always wet. Now that the leaves are gone. I can see the branches are also wet. Another tree I have is perfectly dry and normal. What’s causing this and how can I correct it?

A. This “wetness” was caused by one of the leaf sucking insects, most likely aphids. If you inspect this “wetness” I think you’ll find it is shiny and sticky as well as wet. It probably attracts flies, bees and other insects.

Common occurrence in late fall and early winter before leaves drop are "wet leaves" due to aphids feeding.

            Aphids suck plant juices from the leaves and then exude a shiny, sugary liquid that drops on the leaves, limbs and plants below it. There are about 4000 different kinds of aphids and about 10% of them cause problems to our plants.

            In the eastern US they have a special aphid, called the crape myrtle aphid, that causes these problems only on crape myrtle. Several aphids specialize only on certain plants. But there are also aphids which are general feeders and infest a variety of different plants as well.

In the spring, aphids feeding on new leaves cause the leaves to distort from their feeding. Leaves that have fully developed won't demonstrate this when aphids feed on them.

            Aphids are a huge problem because they reproduce rapidly in the spring without the help of male aphids. Later in the season, females can be found with wings and fly from plant to plant giving birth to living young wherever there are succulent young leaves nearby. If you don’t get them under control, they can spread.

            To add to this problem, ants pick them up and distribute them as well because they like the sugary liquid they produce from sucking plant sap. Controlling ants in the spring is one way to reduce their spread in the spring.

Good reason to clean up your garden area of weeds is to prevent aphids from staying the winter on these plants. They will huddle on the lowest leaves or stem in loose soil or mulch at the soil surface.

            There are lots of predatory insects and even fungi that attack them during the growing season, but their reproduction and spread is so rapid that these biological controls can’t keep up with their rapidly increasing numbers.

            I guarantee there are winged females and overwintering eggs hidden at the base of woody plants and tucked into nooks and crannies on the trunk and stems.

            What to do? Spray both trees with dormant oil this winter to suffocate both the eggs and the overwintering females. These dormant oils are made from paraffin or mineral oil. Neem oil, although it might be effective, is not a dormant oil.

            Select a warm day, without wind and the sun shining, for spraying. Mix the dormant oil with water at the rate recommended on the label. The oil is emulsified and can be diluted with water for spraying.

            Spray the trees from top to bottom, covering the trunk and all the limbs. They like to overwinter at the base of plants where it’s out of the weather so spray there as well. Remove weeds where they can hide during the winter.

Reasons for Palo Verde Limb Dieback

Q. The palo verde tree in our daughter’s yard looks like it has damage. The top has some dead branches in it. We have had to remove some limbs because of this problem. Can it be saved?

A. There are several different kinds of Palo Verde used primarily in desert landscaping. All have tender new growth that can be severely damaged when exposed to intense sunlight. It is important these trees are pruned throughout their lives so that the tree’s canopy shades the trunk and limbs.

If desert adapted trees have limbs removed that expose the trunk or large limbs to direct sunlight and sunburn, borers can be a problem in these trees such as Palo Verde and acacia

            Pruning them in a fashion that exposes limbs and the trunk to intense sunlight causes damage that causes limb death that becomes visible a few years later. It’s a progression that usually starts with bad pruning practices. This progression begins when too much is removed from these trees. When too much is removed, the limbs and trunk are exposed to high intensity desert sunlight.

Exposing the trunk and lower limbs to direct sunlight and sunburn can create future problems to trees like the Palo Verde.

            Intense, direct sunlight on young limbs first causes a discoloration due to intense sunlight. As this direct sunlight repeats day after day, exposed areas of limbs and trunk facing the sun die. Water can’t through dead areas of the trunk and limbs.

            Unless this sunburn causes severe damage, the top of the tree probably looks fine. The tree can still move water around the damaged area from roots to tree branches. The damage could be as much is 50% of the limb and trunk area and the tree looks fine.

This is not Palo Verde but when the trunk and limbs are exposed to intense sunlight for a long period of time, year after year, the intense sunlight can damage or even kill the living part of the tree under the sunburned area. The beginning of this damage can be very attractive to some wood boring insects which can make the damage worse.

            This damage from sunburn attracts insects such as borers that feed on living parts of the tree close to the damaged area. This feeding by borers causes even more damage that reduces water movement to the limbs. Perhaps the first year or two, trunk and limb damage goes unnoticed because the canopy looks fine.

The first sign of sunburn is a discoloration or off-color to the trunk, limbs or even fruit on fruit trees.

            But at some point, damage becomes severe enough that water movement from roots to the canopy is reduced.  Limbs start dying back because the tree can’t get enough water past the damage. This usually happens during the heat of the summer when demand for water is highest.

            The homeowner now notices the limb death in the canopy. The homeowner removes dead limbs. This exposes the tree to more intense sunlight and further damage. Tree damage is so severe and unsightly the homeowner considers removing it. This is the tree “death spiral”.

            What to do? Damage to the tree may be already extensive. Decide whether you can live with this damage or not. If not, have the tree removed. If you decide to keep the tree, then encourage it to heal as quickly as possible. Contribute to this healing by giving it enough water on a regular basis and apply fertilizer in early spring.

High Nitrogen, Quick Release of Fertilizers Keep Plants Green during Cold Weather

Q. Our lawn was beautiful during the summer but started turning brown when it got cold here in Mesquite. This is a fescue lawn and we were told it would stay green all winter long.

A. There are several different kinds of fescue, but the fescue used for lawns is technically called “turfgrass type tall fescue”. Tall fescue lawns stay green through the winter in our Mojave Desert climate if they receive an application of nitrogen fertilizer in late Fall and night temperatures don’t drop below about 15° F.

This is a conventional high nitrogen fertilizer called ammonium sulfate. It is used to feed plants only nitrogen for promoting growth of stems and leaves.Where the nitrogen comes from but conventional fertilizers may contain other ingredients in very small quantities. Some followers of organic principles might call these other ingredients, "contaminants" in the fertilizer. Any fast release slow nitrogen fertilizer will keep plants green longer into late fall and early winter then not applying any nitrogen.

            If the lawn is without nitrogen, and nighttime temperatures drop below freezing, fescue lawns will go dormant and turn brown. Apply a high nitrogen fertilizer or compost to the lawn late in the fall before freezing temperatures.

A high nitrogen fertilizer but derived from dried blood. It is also high in nitrogen and releases it fairly quickly but not as fast as ammonium sulfate. This blood meal is not certified organic by the USDA but many would consider it as "organic" nitrogen.

            You can use any fertilizer if the first number is the highest number on the bag. Examples can be 21-0-0, ammonium sulfate, applied 2–3 weeks before freezing weather hits. In our Las Vegas climate, applications would be around Thanksgiving, or possibly even later if nighttime temperatures don’t drop below freezing.

            Nitrogen, the first number on the fertilizer bag, is responsible for a plant’s dark green color and encouraging new leaf and stem growth. It can also keep plants from going dormant during the winter.

            There is a nefarious side to late applications of nitrogen. Nitrogen applications made in late Summer or early Fall can compromise our winter-tender plants such as many types of citrus. Applications of high nitrogen fertilizer to these plants late in the growing season can cause them to be more susceptible to freezing temperatures. Never apply high nitrogen fertilizers during Fall to plants that might freeze during winter the winter.

Best Time and How to Prune Ornamental Shrubs

Q. I have some shrubs in my yard that are getting rather scraggly looking.  I was wondering when and how far back I can prune it back in to shape.

Shrubs improperly pruned with a hedge shears. Unfortunately, most people do not recognize bad pruning when they see it and now unfortunately are asking for this kind of pruning.

A. First decide if now is the best time for pruning them or not. You can prune anytime during the winter months. Some plants look better through the winter if they are pruned now. Other plants look fine now but might not look as good if you were to prune them.

As shrubs are pruned more and more into a gumball, in a few years they developed exposed strong stabs at the base.

            Remember, if you prune now you will have to look at them the rest of the winter. If these are flowering shrubs, prune them soon after they finished flowering. If the shrubs do not have ornamental flowers, prune them anytime during the winter.
            The best pruning methods remove the oldest growth from the bottom of the shrub with a lopper or hand shears. Hedge shears for pruning shrubs are, as the name implies, for hedges, not for shrubs.

Properly pruned shrubs require to – 4 cuts at the very bottom to keep it looking good and juvenile.

Organic vs Conventional Strawberries: Nutrition and Pesticide Residues

Organic and conventional strawberries: nutritional quality, antioxidant characteristics and pesticide residues

https://www.pubhort.org/fruits/73/1/5/index.htm

H.B. Kobi1, M.C. Martins1, P.I. Silva1, J.L. Souza2, J.C.S. Carneiro1, F.F. Heleno3, M.E.L.R. Queiroz3 and N.M.B. Costa1,a

1 Federal University of Espirito Santo, Center for Agrarian Sciences, Alegre, 29500-000 ES, Brazil

2 INCAPER – Centro Serrano, Venda Nova do Imigrante, 29375-000 ES, Brazil

3 Federal University of Viçosa, Department of Chemistry, Viçosa, 36570-000 MG, Brazil

What is already known on this subject?

Organic farming may affect the food composition and produce healthier foods than the conventional system, characterized by intensive use of chemical products.

What are the new findings?

Organic farming produced pesticide-free fruits but did not imply on substantial changes in the nutritional quality or antioxidant properties of strawberries.

What is the expected impact on horticulture?

It is expected to encourage the organic farming system in order to produce healthy and pesticide-free strawberries.

SUMMARY

Introduction – Organic farming system may affect the food composition and produce healthy foods. The aim of this study was to compare the nutritional quality, antioxidant properties and pesticide residues of organic or conventional strawberries.

Materials and methods – In a first experiment, organic and conventional fruits from the cvs. Camarosa and Albion were obtained directly from the farmers. Subsequently, ‘Camarosa’ was produced in organic and conventional systems, under controlled conditions. Pesticide residues were analysed in the second trial and the remaining parameters were evaluated in both experiments.

Results and discussion – In the first experiment, the fruits of organic cv. Albion showed higher moisture (91.8%) and lower total solid (8.2%), and carbohydrate (5.7%) contents. ‘Albion’ fruits also showed higher total solid content than ‘Camarosa’ fruits in conventional farming system. Pesticide residues were not detected. Under controlled conditions, organic ‘Camarosa’ fruits had higher moisture (91.5%) and ash (0.4%) contents, whereas conventional strawberries had higher soluble solids (8.5 °Brix), proteins (0.9%) and anthocyanins (17.7 mg 100 g-1). Residues of azoxystrobin, lambda-cyhalothrin and thiamethoxam were detected at values below the limit of detection (<LOD) in all organic samples, and below the limit of quantification (<LOQ) in conventional strawberries.

Conclusion – Organic and conventional production systems do not promote any expressive difference in the nutritional quality or antioxidant properties of strawberries, although the organic farming produced pesticide-free fruits.

Résumé

Fraises biologiques et conventionnelles: qualité nutritionnelle, propriétés anti-oxydantes et résidus de pesticides.

Introduction – Le système d’agriculture biologique peut affecter la composition des aliments et produire des aliments sains. Le but de cette étude était de comparer la qualité nutritionnelle, les propriétés anti-oxydantes et les résidus de pesticides des fraises produites en système biologique ou conventionnel.

Matériel et méthodes – Dans une première expérience, les fruits biologiques et conventionnels des cvs. Camarosa et Albion ont été obtenus directement auprès des agriculteurs. Par la suite, les fraises ‘Camarosa’ ont été produites en systèmes de culture biologique et conventionnel, en conditions contrôlées. Les résidus de pesticides ont été analysés dans le deuxième essai et tous les autres paramètres ont été évalués dans les deux expériences.

Résultats et discussion – Dans la première expérience, les fruits biologiques du cv. Albion ont présenté des teneurs en eau (91,8%) plus élevées, et des teneurs en matières solides totales (8,2%) et en hydrates de carbone (5,7%) plus faibles. Les fruits d’‘Albion’ avaient également une teneur en solides totaux plus élevée que ceux de ‘Camarosa’ produits en système de culture conventionnel. Aucun résidu de pesticides n’a été détecté. En conditions contrôlées, les fruits biologiques de ‘Camarosa’ avaient des teneurs en eau (91,5%) et en cendres (0,4%) plus élevées, tandis qu’en conventionnel, les fraises contenaient plus de matières solubles (8,5 °Brix), de protéines (0,9%) et d’anthocyanes (17,7 mg 100 g-1). Des résidus d'azoxystrobine, de lambda-cyhalothrine et de thiaméthoxam ont été détectés, à des valeurs inférieures à la limite de détection (<LOD) dans tous les échantillons biologiques et inférieures à la limite de quantification (<LOQ) dans les fraises conventionnelles.

Conclusion – Les systèmes de production biologiques et conventionnels ne favorisent pas l’expression de différences de qualité nutritionnelle ni de propriétés anti-oxydantes des fraises, même si l’agriculture biologique produit des fruits sans pesticides.

This is a peer reviewed publication appearing in the International Journal for Tropical and Subtropical Hortculture

Fruits 73 (1) 39-47 | DOI: 10.17660/th2018/73.1.5
ISSN 0248-1294 print and 1625-967X online | © ISHS 2018 

Why Cleanup Around Fruit Trees and Vegetable Gardens

Survival of pathogenic Colletotrichum isolates on dormant buds, twigs and fallen leaves of apple trees in commercial orchards

https://www.pubhort.org/fruits/72/3/5/index.htm

N.A. Hamada1,ª and L.L. May De Mio2

1 IFPR, Paraná Federal Institute of Education, Science and Technology, Palmas, Rodovia PRT, 280, Trevo da Codapar, 85555-000 Palmas, PR, Brazil

2.UFPR, Federal University of Parana, Department of Crop Protection, 80035-050, Curitiba, PR, Brazil

Introduction – Glomerella leaf spot on apple (Malus × domestica Borkh.), due to a complex of Colletotrichum species, causes severe leaf spot symptoms leading to early leaf fall, and eventual symptoms on fruit before and after harvest. Under the Brazilian conditions, it is the main apple disease responsible for severe damage in all production areas. This study aimed 1) to verify the survival of Colletotrichum spp. in dormant organs, fallen leaves and soil samples from fungicide-sprayed commercial orchards during winter; 2) to verify the survival of Colletotrichum spp. on asymptomatic leaves during the vegetative period; and 3) to identify the species complex and to confirm the pathogenicity of the isolates obtained from different parts of the plant (on fruit and leaves).

Materials and methods – The study was conducted in a commercial orchard during the winters of 2010 and 2011, assessing the pathogen survival on buds, twigs, asymptomatic leaves, fallen leaves and soil samples. Fungal isolates from different substrates were inoculated on fruit (with and without wound) and on leaves of apple cv. Gala to prove their pathogenicity.

Results and discussion – This is the first investigation on the survival of the Colletotrichum complex in apple under the conditions of Brazilian commercial orchards. All isolates (16) from dormant twigs and fallen leaves were identified as C. acutatum species complex. Five (5) isolates from dormant buds were identified as C. gloeosporioides species complex and three (3) as C. acutatum species complex. According to the data collected, Colletotrichum spp. are able to survive during winter in dormant buds, on dormant twigs and fallen leaves, but are most frequent on fallen leaves. The isolates obtained from buds, twigs and fallen leaves were pathogenic on leaves and fruit of apple. Copper sprays during the dormant stage did not completely eliminate the inoculum. The pathogen was not recovered from soil or from asymptomatic leaves with the methodology used.

Conclusion – Fallen leaves on the ground can be a source of inoculum from one season to the next, so they must be considered in disease management programs to avoid the spread of primary inoculum.

My Comments. This again points to the importance of sanitation in growing areas. Pick up fallen leaves, old fruit, remove remaining fruit from fruit trees, and do not leave old debris from the orchard or garden in the growing area unless it has been properly composted. Most other types of plant materials left as a surface mulch not related to the garden or fruit trees is fine.

Fertilizer Improves Yield of Cactus Fruit

Effects of nitrogen and phosphorus fertilization on fruit yield and quality of cactus pear Opuntia ficus-indica (L.) Mill.

https://www.pubhort.org/fruits/72/4/3/index.htm

M. Arba1,a , A. Falisse2,3, R. Choukr-Allah1 and M. Sindic4

1 Department of Horticulture, Hassan II Institute of Agronomy and Veterinary Medicine, Horticultural Complex of Agadir, Morocco

2 Crop Production Unit, Gembloux Agro-Bio Tech, Liège University, Belgium

3 Faculty of Agriculture, University of Agricultural Sciences and Veterinary Medicine, Cluj, Romania

4 Quality and Food Safety Laboratory, Gembloux Agro Bio Tech, Liège University, Belgium

What is already known on this subject?

Studies on mineral fertilization of cactus pear were carried out in some countries where cactus pear is cultivated. Several authors reported that mineral fertilization increased fruit yield, but some of them have indicated that fruit quality could be affected by fertilization.

What are the new findings?

Obtained results showed that nitrogen and phosphorus mineral fertilization improved fruit yield, mainly fruit size (weight and dimensions). Fruit quality was not significantly affected. Mineral fertilization also increased the emission of buds and of shoots.

What is the expected impact on horticulture?

Understanding the effects of nitrogen and phosphorus mineral fertilization on fruit yield and quality of cactus pear. The improvement of cactus pear managing practices, mainly the application of fertilizers, pruning and harvesting. The improvement of the socio-economic life of the farmers and the rural populations in the arid

SUMMARY

Introduction – In order to optimise the nitrogen (N) and phosphorus (P) fertilization of cactus pear in arid regions, we decided to determine its effects on the yield and fruit quality as well as on the plant phenology.

Materials and methods – Five N-P dressings were compared on the spineless cv. Moussa in the Agadir area: 0–0, 0–80, 40–40, 60–0, and 60–80 (in kg N ha-1 – kg P2O5 ha-1) over two consecutive growing seasons (2011 and 2012). Yield components and physico-chemical characteristics of the fruit were recorded at harvest.

Results and discussion – Although in 2011 the applications of N and P had no effect on fruit yielding, in 2012 the dressings 60N or 80P alone increased the yield by +3.0 and 6.1 kg plant-1, respectively, compared with the control. Combining both N and P at the same rate resulted in a maximum yield of 14.9 kg plant-1. Fertilization had positive effects on flowering rates, fruit size and fruit number, and did not modify the content of pulp, the juice content, peel thickness, the juice dry matter, the pH, titratable acidity, total sugars and soluble solids. It also did not modify the dates of flowering and of ripening. Nitrogen dressings significantly increased the number of emitted buds and emitted shoots on one-year cladodes by four fold.

Conclusion – Relevant N-P fertilization significantly improved fruit yield, the number of fruits per plant and fruit size in particular. Long term and postharvest effects shall be further studied.

Résumé

Introduction – La fertilisation azotée (N) et phosphorique (P) du figuier de Barbarie a besoin d’être optimisée en zone aride. Cette étude vise à en évaluer les effets sur le rendement et la qualité des fruits et à en décrire les effets sur la phénologie de la plante.

Matériel et méthodes – Cinq fumures N-P ont été comparées pendant deux années sur la variété inerme ‘Moussa’ dans la région d’Agadir: 0–0, 0–80, 40–40, 60–0, et 60–80 (en kg N ha-1 – kg P2O5 ha-1). Les composantes du rendement et les caractères physico-chimiques des fruits ont été enregistrés à la récolte.

Résultats et discussion – En 2011, les différents niveaux de fertilisation n’ont pas eu d’effet sur le rendement alors qu’en 2012, l’interaction entre N et P était très significative. En comparaison avec le témoin, l’apport de 80P ou de 60N a augmenté le rendement de +3,0 et +6,1 kg plante-1, respectivement, et le traitement 60N + 80P de +14,9 kg plante-1. Les traitements fertilisants ont eu des effets positifs sur le nombre de fleurs et le nombre de fruits formés, ainsi que sur le calibre des fruits; en revanche, ils n’ont pas eu d’effet significatif sur la teneur en pulpe et en jus de fruits, l’épaisseur du tégument, la teneur en matière sèche du jus, le pH, l’acidité titrable, les sucres totaux et matières sèches solubles. Ils n’ont pas nettement modifié les dates de floraison et de maturation des plantes. Cependant, l’apport d’azote a augmenté le nombre de bourgeons émis par cladode et le nombre de pousses sur les cladodes d’un an, jusqu’à le multiplier par 4 environ.

Conclusion – Une fertilisation N-P appropriée permet d’améliorer de façon significative le rendement en fruits des cultures de figuier de Barbarie en condition aride, en particulier le nombre de fruits par plante et le calibre des fruits. Les effets dans la durée et en post-récolte doivent encore être étudiés.

My Comments. This is another study that demonstrates increased yield of cactus pear (aka beavertail cactus) fruits when fertilizer is applied. Water must be applied more carefully because of damage to the plants if watered too often. But this paper also addresses fruit quality to some degree. Sensory evaluation is not considered but fruit quality is measured by laboratory equipment rather than by people tasting it. Sensory evaluation is hard to judge using laboratory equipment.

Using Pheromone Traps to Control Wormy Apples

Q. We have six apple and two pear trees in Ely, Nevada. This year all the fruit had worms in them. The damage started when the apples were only about 1 inch in diameter. Every single fruit had worms in them. I am suspecting a moth but I’m not sure. We sprayed with Neem Oil before they blossomed and after the fruit set. Any ideas?

A. This “worm” is the juvenile or immature form of a moth called the codling moth. They ruin the apples or pears by devouring the inside of the fruit leaving their feces and allowing for the fruit to start rotting. Hence, “wormy apples” which can look disgusting later. In commercial apple and pear production, as many as eight “cover sprays” are applied to the trees every year to prevent wormy apples.

An early sign your apples may be wormy. The codling moth lays an egg on the outside of immature apple or pear fruit. The warm hatches and tunnels inside the apple. Conventionally, insecticides are sprayed on the trees and fruit to kill the warm before it enters the fruit.

            Codling moth is the most destructive insect of apples and pears in the world. We see codling moth damage to apples and pears in the Las Vegas area as well. But because we are in the Mojave Desert, this pest is not as damaging as it could be. As more homeowners plant more fruit trees however, we will see more of this pest creating damage to these fruits in the future.

This is a winged sticky trap with a reddish brown rubber lure that was impregnated with a pheromone. This sex hormone is released into the air and one gender of the past is lured to the trap where it is stuck. When the sticky bottom of the trap is full or no longer sticky, it is replaced. In a dusty environment this can be weekly. The lure weakens over time and is replaced to keep the scent at its maximum filling the air.

            As I mentioned in passing, one method of control is using insecticides as a “cover spray”. A cover spray is an insecticide sprayed over the entire tree, not just the fruit. Sprays are applied often enough to create a poisonous barrier for the female codling moth. Neem oil will not work in this way against this pest.

This is a Delta trap used mostly for monitoring when the moth is flying. It does a great job telling you when sprays are needed. I like the trap better when relying only on disrupting the mating of insects for control.

            If you choose to use an insecticide, it must be something other than Neem oil and it must be sprayed frequently over the entire tree. There are insecticides you can purchase from the store but the secret is to apply it often beginning when the fruit first begins to develop.

            Another option, pheromone traps, can either reduce the number of times the tree is sprayed or even eliminate spraying altogether. Pheromone traps are cardboard traps which contain a sex hormone released into the open air. This pheromone prevents the male codling moth from finding a female and, instead, gets stuck in a sticky mess inside the trap.

            Under some circumstances, these pheromone traps may catch enough males to prevent female moths from laying their eggs. This interruption in mating can prevent wormy apples from occurring.

When to Apply Fertilizer and What Kind Explained

Q. When during the year should you start and stop fertilizing landscape plants and what kind of fertilizer is best for them all? It seems to me that with acid loving plants, cacti, palms, roses, fruit trees and annual flowers they might all require different kinds of fertilizers and different times to apply them.

A. You could go crazy trying to follow all the different rules when fertilizing for different types of plants. Keep it simple. Let me give you a few simple rules to follow when applying fertilizers.

This is an easy fertilizer for homeowners because it tells them what it's for. It has 10% nitrogen, 5% phosphorus in the form of P205 and 10% potassium in the form of K2O. But it should really tell us that it's primarily for frond and stem growth (nitrogen), half as much for roots and flower production (phosphorus, we don't want much of that anyway) and a similar amount of potassium as nitrogen. What other plants would this be good for besides palms?

            If plants are winter tender, in other words they might get hurt or die when temperatures dip below freezing, stop fertilizing these plants in July. Our citrus trees fall into this category.

            Lawns, bedding plants, such as annual flowers, and vegetables should be lightly fertilized once a month. Lawns that are expected to remain dark green during the winter should have fertilizer applied around Thanksgiving before freezing weather.

This is 21% nitrogen in the form of ammonium sulfate. There is no number for on this label but it also delivers about 20% sulfur as a fertilizer as well. Some people are very negative about ammonium sulfate but the plant doesn't really care where the nitrogen is coming from. We should pay attention to any contaminants, such as heavy metals, that might be in this bag of fertilizer.

            For light fertilizer applications, reduce the amount applied to half the rate recommended on the bag or container. Light applications of fertilizer can be applied every month and immediately watered in if applied early in the morning. Get in the habit of applying fertilizers early in the morning or late in the day.

            The most highly prized landscape plants should be fertilized three or four times during the year; January/February, April/May and September/October. These include plants like roses, gardenias, and Jasmine for instance. Again, use half rates when applying fertilizers.

Has a lot of phosphorus in it. The numbers tell us that. This fertilizer would be used for new plants that need to create a lot of new roots and those that flower or produce seed. Marijuana producers use this type of fertilizer when the plant is getting older and is close to flowering and producing seeds.

            Most landscape plants are fertilized only once, just before new growth begins in late January or early February. This includes all landscape trees including palm trees.

            Which fertilizer to use? You can get by with 2 or 3 fertilizers in your arsenal. That’s all. Fertilizers have three numbers separated by hyphens somewhere on their label. They represent three different plant nutrients; nitrogen, phosphorus and potassium and in that order.

            When growing plants that are primarily important because of their leaves and stems, the first number, or nitrogen, should be the highest. The middle number, phosphorus, should be about one fourth of the value of the first number. The last number, or potassium should be somewhere in between the first and second number.

Obviously then when growing roses, fertilizers with a high middle number are important for good flower production. Be careful of adding high phosphorus fertilizers over and over because phosphorus will begin to accumulate in soils unlike nitrogen and potassium.

            When growing plants valued for their flowers or fruit, then the second number or phosphorus becomes critical. It needs to be the highest. When fertilizing these plants, the second number should be highest while the first and third numbers lower. Exact numbers are not critical but the ratio of these three, or their proportions contained in the fertilizer, is more important

            To be healthy, plants need more nutrients than supplied by only these three numbers. But these three numbers represent nutrients needed in massive amounts by plants. The other important nutrients are supplied by the soil. For this reason, I frequently mention the application of compost. A compost application, once a year to landscape plants, would be extremely beneficial.

Olive Tree Suckers Easily from Many Locations

Q. An olive tree on the property of our homeowner association is sending up suckers from its base and along the trunk. I am thinking it’s because the tree is not getting enough water. Our landscaper continues to remove them and thinks otherwise. Who is right?

A. Suckering from the base can be a sign of a lack of water in some trees but olive trees also sucker from the base and along the trunk easily. If you look at the base of older olive trees you will see some “knots” or swellings attached to the lower trunk, trunk limbs and root flares as they get older. There can be so many of them the tree becomes disfigured. It gives olive trees a great deal of character in their old age.

Olives sucker easily from clusters of immature or unopened buds hidden on the trunk. You can spot them as bumps or gnarls. A limb was removed from this olive tree which encouraged the suckers to grow.

            These swellings along the trunk and limbs develop from clusters of immature buds embedded in woody growth. Suckers can originate from these “knots”. These knots or “burls” can get quite massive in older trees.

            Burls are common in other trees as well particularly trees that are prone to damage from fire or animals like coastal redwoods. Burls are valued by many woodworkers but despised by the construction lumber people.

            Suckering from the base of some trees, however, can be in response to drought. There may or may not be obvious swellings at the base of these trees. The tree finds it difficult to deliver water to its top when water is scarce.

This tree rose suckered from the rootstock after the top of the tree, or scion, died back.

            These clusters of undeveloped buds, previously asleep, begin growing from the base. Some are scattered through the wood and others are in clusters. Growth from the bottom is easier to support when water is scarce then growth at the top.

            Some trees like many ash trees don’t have that survival mechanism. When water is scarce, their leaves begin to scorch, push very little new growth and limbs dieback particularly during hot weather.        

            You could still be right. The tree may not be getting enough water and that just makes suckering even worse. It’s best to look at the tops of the trees to make a drought determination. When water is scarce, the canopy growth suffers and when water is really restricted there is leaf scorch and dieback by the tallest limbs.          

            If the tree is growing nicely and has lots of leaves then I would say it's getting enough water. The suckering at the base of the tree is probably normal. However, if the tree is sparse in its canopy and growth is poor and it is suckering from the base then I would worry about enough water.

Acacia Dropping Its Leaves

Q. My young acacia tree has abundant growth but only on the top half of the branches. Each of these branches are losing many leaves half way up the branch. There is a lot of growth at the top of the tree but not much below. Am I watering too much, too little? I water every five days during the summer.

A. Acacia trees are desert plants. Most desert plants are opportunists when it comes to using water. In other words, when water is present they grow like crazy. When water is absent, their growth slows and they then try to use as little water as possible. Desert plants may even stop their growth and drop their leaves when water is not available!

This is not Acacia but Palo Verde. Boring insects, or borers, may feed on a variety of trees and shrubs or very specific ones. Borers, like the flat headed apple tree borer, has a variety of trees they attack including the desert trees. Sometimes they attack trees with sun damage and other times they seem to attack trees without any cause at all.

            All plants are tremendous competitors for water, nutrients and light. They want to be “top dog” in their plant community by taking as much water, nutrients and light as possible when it’s available. By doing this, they take away these building blocks of growth from other plants.

            When water is present, trees try to get as tall as possible as rapidly as they can before they start to fill out. They grow upward first and then put energy into horizontal growth once they’ve established some height. This growth in height takes away light and shades competitors. This early growth in height, when there is a plenty of water and nutrients, oftentimes is at the expense of putting on lower growth .

We commonly see borers attack fruit trees and many different landscape plants. This flat headed Appletree borer infested a young Apple tree recently after was planted. The tree was so young that extensive damage was done by a single borer found feeding in the tree.

            Watering schedules take two different forms; how much water is applied and how often water is applied. It’s difficult to say with certainty without seeing the tree, but it sounds like it is receiving water too often.

            Watering every five days means nothing to me. I can take a sip of water hourly and someone might think I am drinking plenty of water. But another person might ask, how big are your “sips”? One teaspoon or 1 pint?

            How much water to apply? When watering trees, give them enough. Apply enough water to wet the soil at least 24 inches deep. Apply this water to at least half the area under the canopy of the tree. Once it enters the soil, the water spreads horizontally further than this.

Use 3 eighths inch rebar to estimate how deeply water has penetrated into the soil after an irrigation. Check the soil in 3 or 4 locations.

            Use 3/8-inch diameter rebar that is three feet long. After irrigating, push this rebar in the soil in three or four locations to check the watering depth. Wet soil allows the rebar to slip in easily to the same depth as the wet soil. Dry soil makes it hard to push further.

            It should slip into the soil at least 24 inches deep. Once you know how many minutes this takes, the amount of time you water won’t change. Each irrigation will be 24 inches deep.

            If using drip irrigation, space emitters about 2 feet apart. If using a basin or moat under the tree, the basin should be as wide as half the area under the canopy. Trees grow. This means the basin must expanded every three years. If using drip emitters, add more emitters every three years.

Basin under a tree used to capture the water for irrigation. If using a hose or some other delivery method that releases a large quantity of water rapidly, a basin is required to keep the water from going everywhere else but around the tree.

            How often to apply water? Look at the tree canopy. It will tell you. When the canopy of the tree starts to thin out, it’s time to irrigate! Desert trees tell you when to water when their canopies begin to thin out.

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

https://www.eventbrite.com/d/nv--las-vegas/fruit-tree-pruning

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.

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.

http://www.barkbeetles.info/regional_chklist_target_species.php?lookUp=491

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

ABSTRACT
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.

http://npic.orst.edu/factsheets/neemgen.html

Look here for Wikipedia on Neem Oil Uses

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.

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.