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    Citrus Simplified

    Mealy bugs are destroying my young citrus! What do I do?

    Mealy bugs are destroying my young citrus! What do I do?

    Cheri Abraham, PhD
    Entomologist & Operations Manager,
    US Citrus, LLC

     

    Mealybugs are one of the most common pests on indoor plants in general and even on citrus plants grown indoors or in greenhouses. They look like white fluffy substances that mostly congregate on tender leaves.

    Mealybugs actually are tiny soft-bodied insects. Females lay eggs in a yellow pouch out of which the young ones (crawlers) emerge. This is the stage when these insects are most susceptible to any chemical control measure. As times goes by, they secret a white fluffy outer covering, which essentially acts like a jacket, preventing chemicals to penetrate and kill them. This is simply why mealybug control becomes a difficult task in many situations. Often attracted to lush green and soft plants, mealybugs use their piercing and sucking mouthparts to feed on plant fluids. The feeding itself can cause defoliation and stunted growth. Further, they secrete honeydew which causes fungus to grow as a secondary infection and also have ants grow into a symbiotic relationship with the mealy bugs.

    If you miss the white fluffy congregation on the plant, you will definitely catch the black coating on leaves, and that observation by itself could throw off the control measure. Since the black color is a fungus, often times, people apply fungicides, but as long as the root cause remains, the secondary infection cannot be controlled completely.

    When Ants get into a symbiotic relationship with the mealybugs, they protect the mealy bugs in exchange for the honeydew (sugary solution) that is secreted by the mealybugs. This often times also defeat natural or augmented biocontrol.

    More often than not, on plants grown outdoors, mealybug populations do not increase to an extent that warrants active control measures unless there is a factor working against. A prime example would be pesticide sprays that kill existing populations of natural enemies.

    How to rid your plants of mealybugs.

    Oftentimes, a healthy plant is a first step and the best defence against mealybugs. In situations where plants are crowded and overly moist, a humid pocket does build up and favor mealybug populations as well.

    If you already have mealy bugs, there are different ways to go about getting rid of them.

    1. Mechanical: by spraying water with some pressure, you will be able to dislodge the mealy bugs off the leaves. This would have to be repeated as often as you check and find mealybugs on the plant.
    2. Biocontrol/ Natural control:
      1. Ladybeetles,
      2. parasitic wasps,
      3. lacewings

    All three mentioned above are natural enemies of mealybugs. They can be purchased and released in your greenhouses. They will be less suited for an indoor (inside the house) growing situation. Something to be cautious about: the presence of ants protects the mealy bugs from these natural enemies. So the Ants need to be controlled before releasing natural enemies.

                   4. Entomopathogenic fungus like Beauveria bassiana: is applied like an insecticide but contains the fungus that would control mealy bugs.

    1. Chemical:
      1. Organic:
        1. Soaps: 1 tsp of hand soap or detergent soap in a gallon of water. Avoid any additives or fancy ingredients.
        2. Botanical Oils: Neem oil derivatives sprayed at the label rates can keep the plant clean and free from mealybugs. Also available are oils extracted from other plants like Rosemary and other herbs.
        3. Homemade sprays: Various homemade concoctions using vinegar, hot sauce and garlic are effective to control mealybugs and other pests.
        4. Pesticides: Spinosad is an organic option for chemical control. Follow label rates.
      2. Inorganic:
        1. Pesticides: Systemic pesticides (like Imidacloprid, which is the chemical name) that move inside the plant are your best bet. Once the white fluffy substance covers the mealy bugs, it is difficult to get control using chemicals. This warrant sprays every week in an effort to hit the newly emerged crawlers, which are most susceptible to insecticides.

     If there are just a few mealybugs here and there, you can just pinch the plant portion containing the mealybugs and trash them in a ziploc bag. If you are more of a bug enthusiast, you could watch them a little closer and marvel at the intricacies of their life cycle!

     Suggested readings:

    Integrated pest management of mealybugs

    Managing mealybugs in greenhouses

     

     

     

    Mistakes I have made growing lemon, lime, orange, Kaffir lime, calamondin, and Kumquat trees: Underwatering

    Overwatering and Underwatering Citrus Trees

    In general, there is advice that says you should not overwater your citrus tree.  This is important for all varieties of citrus trees, including lemons, limes, grapefruit, Calamondins, Kaffir lime, and Australian finger limes. This is because when you are talking about watering, you are primarily concerned about its effects on the root system.

    Overwatering Citrus Trees

    If citrus is overwatered, it can lead to a condition called root rot, caused by the Phytophthora pathogen, a fungal infection. In citrus groves, it is especially a problem where fields are flood irrigated. This is when, as the name implies, the entire field is floated using a system of pipes as irrigation. In these conditions, it is much easier to spread the fungal spores.

    The roots can really be affected, especially when the roots are saturated in water.  This is especially a problem when there is poor drainage of the soil. Well-draining soils ameliorate this problem, for example in the Rio Grande Valley, where US Citrus plants Eureka lemons, Meyer lemons, Persian limes, Kaffir limes, and Rio Red grapefruits, we do so in areas where there is good Sandy soil subtype. This Sandy loam soil is extremely well draining. Also, we used exclusively drip irrigation; this makes the control of potential fungal root rot of citrus trees much easier, minimizing risk.

    The reason that issues for watering remains the same between different varieties of citrus is that citrus trees are all grown from a rootstock, think of a citrus tree as two different trees fused together. That is the grafting process that is done at US Citrus nurseries. So basically, the roots of all of the trees are the same, as we use either a sour orange or trifoliate rootstock, and the citrus variety differences are in the top parts of the tree.

    Now getting to practical points for the backyard gardener, here at US Citrus we recommend that nearly all gardeners growing citrus in the United States grow their trees in pots. This is so that they can bring them indoors or in a garage during the wintertime. Only areas in the southernmost United States like the states of California, Florida, Texas, Louisiana, Arizona, Georgia can support citrus being grown in the ground. All other areas, citrus planted in the ground will die from freezing weather.

    Because of this unique situation of growing citrus in pots, this throws the old adage of not overwatering your citrus upside down. It is extremely hard to over water citrus that is kept in a well-draining pot and is outdoors. Especially in the summertime and in hot area conditions, we have never seen had an issue with a customer who has overwatered their citrus tree. However, we have had multiple customers send us pictures of citrus trees doing poorly from underwatering.

    This is because the citrus tree is in a pot, using standard potting soil, and if it has good drainage holes on the bottom, or it is a mesh type pot which allows good aeration and drainage throughout the fabric type pot, then you are effectively controlling the drainage and making it excellent.

    The only time we have experienced customers having problems overwatering is when they are keeping the trees indoors. At this time, there is often a garden saucer placed underneath the tree, and if the garden saucer is full of water and there is constantly water being poured into the soil, this will become waterlogged and the citrus tree will wilt and die.

    Underwatering Citrus Trees

    Underwatering is especially tough on your tree when it is young, growing, and trying to establish a good root system. We recommend our baby trees to be watered 1-2 gallons at its base daily for one month, then follow our citrus tree care guide instructions we send you.

    I myself have moved my 15 citrus trees in pots, and in the wintertime, I moved my trees into the garage. I did use a space heater for a period of time while I was away. I made the mistake of not having a garden saucer underneath every tree fully saturated with water, knowing that I would not be watering for about 10 days.  When I got back from a vacation of 1 week, my citrus trees, even though it was wintertime and they were inside a watch with no lights, they all suffered from dehydration because of the dry heat from the space heater. So, it is important to watch your citrus tree for signs of underwatering year-round. This will manifest as leaf drop, browning and wilting of the leaves, the soil being somewhat dry to touch, and the lack of vigor overall of the tree.

    One friend of mine adores his citrus trees. He had some construction being done in his backyard, so he moved his trees into the garage to protect them. However, this was summertime in West Texas, and garages can get 120 degrees or hotter! Unfortunately his well-cared for, thriving trees died in just 2 days in that extreme heat because he neglected to significantly increase the water needed for those trees. If the situation could not be avoided, I would have recommended a garden saucer with 5 lbs of ice placed around the saucer every day it was in the garage. 

    Like my father, Dr. Mani Skaria, says, “It is very important to look at your tree and assess for signs of overwatering and underwatering.” And from our experience, it is much easier to underwater your citrus tree than it is to overwater!

     

    References:

    Contributor. "How Much Water a Citrus Tree Needs a Week?" Home Guides | SF Gate, http://homeguides.sfgate.com/much-water-citrus-tree-needs-week-57157.html. 15 March 2018.

    Rouse, R. E., & Zekri, M. (2015, February 05). Citrus Culture in the Home Landscape. Retrieved from http://edis.ifas.ufl.edu/hs132

    What is the Orange Dog Caterpillar that Damages Your Lime, Lemon and Orange Trees in Your Backyard?

    About the Orange Dog Caterpillar and its effect on citrus trees

    Mani Skaria, Ph.D.

    Founder & CEO of US Citrus, LLC

    Professor Emeritus, Texas A&M University-Kingsville

    www.uscitrus.com

     

    Orange dog is an enemy of your citrus trees. Some features include:

    1. Looks ugly, has an appearance of bird poop with creamy white markings
    2. Foul odor
    3. Orange dog eats the small leaves of your citrus trees
    4. Its mother is the giant swallowtail butterfly that lays small eggs on citrus leaves. The egg transforms into the next stage called a caterpillar larva with 1½ to 2-inch size with the above three characteristics.
    5. The stinking mechanism is the result of a unique defensive tool of this group of insects. When orange dogs are challenged by an enemy (predators -ants, spiders, mantids). The osmeterium is a gland with an ability to protrude as needed. The gland stores pungent chemicals containing hydrocarbons, terpenes, acids, and ester.

    Nature's way of protecting a baby of a butterfly!

    Orange Dog Caterpillar

    Figure showing an adult butterfly, various camouflage stages of orange dog caterpillar, feeding damage and tongue-like osmeterium. Picture source: University of Florida and UCR. 

    How would you kill your enemy, Orange dog? 

    They are short-term enemies. Show your biblical tolerance and practice co-existence because, in a short period, they will emerge into a beautiful butterfly. But if the number of enemies is high and the damage exceeds your tolerance level, you may do one of the following:

    1. a) Squeeze each one or
    2. b) Collect and place them in a plastic bag and dispose it of
    3. c) Spray soapy water
    4. d) If you want to be aggressive, apply some bacterial toxin as a biological control agent. Bacillus thuringiensis is a bacterium, its toxin, the BT-toxin is commonly used as a biological control agent. And it is readily available. Interestingly, this bacterium naturally occurs in the gut of caterpillars.

    Remember, the orange dog is an irony. One side is an ugly-looking, stinky, poop-like creature with camouflage and chemicals in its pouch. But one day it transforms into one of the natural beauties – an adult, beautiful, butterfly with a great Latin name, Papilio cresphontes, many looks like Oncidium orchids.

    Kaffir lime and tree - history, drinks and characteristics

    All about the Kaffir Lime

    Mani Skaria, Ph.D.

    Founder & CEO of US Citrus, LLC

    Professor Emeritus, Texas A&M University-Kingsville

    www.uscitrus.com

    Thailand is in the center of Southeast Asia, 68 million people, with Bangkok the capital city. Thai people migrated from Southwest China to Southwest Asia. Thailand is rice producer. Thai food is known for its enthusiastic use of fresh herbs and spices. The flavors in Thai food come from garlic, galangal, coriander/cilantro, lemongrass, shallots, pepper, Kaffir lime leaves, shrimp paste, fish sauce, and chilies. This article is dedicated to Kaffir lime fruit and Kaffir lime leaves.

     Kaffir Lime Thailand

    The Nomenclature 

    -    The botanical name, Citrus hystrix

    -    Known with over 20 different official, Latin synonyms

    -    Jeruk purut in Indonesia

    -    Jiàn yè chéng in Chinese

    -    Kkabuyaw or kulubot in the Philippines

    -    Limau purut in Malaysia

    -    Trúc or chanh sác in Vietnam.

    -    Thai lime in South Africa

    -    And in Thailand, it is called Makrud or Makrut (มะกรูด)

    And confusingly, the above name is also used in Thailand for the bergamot orange

    The tree, fruit, and leaves

    -    A tree that may grow to 35 feet tall

    -    Leaves are distinctly-shaped in the citrus family -double leaves

    -    Green rough fruit, bumpy exterior appearance

    -    Fruit ripens to yellow

    -    Fruit size, 2-inch wide.

    -    The leaves are the most frequently used part of the plant, fresh, dried, or frozen, for dishes such as Tom Yum – a hot and sour Thai soup cooked with shrimp and famous, worldwide (figure below).

    Kaffir Lime Curry

    -    The peel of the fruit is commonly used in Lao and Tai curry paste; it adds an aromatic, astringent flavor.

    -    The zest is used to impart flavor in rums

    -    For tastes in rums

    -    Crystallized and candied fruit

    Medicinal use

    -    Traditional medicine in Asian countries

    -    Juice as hair shampoo

    -    To kill head lice

    A Texas distillery called, Treaty Oaks is using Texas-grown Makrut lime (Kaffir lime) zest for the quality gin they produce. https://www.treatyoakdistilling.com/

     

    Kaffir Lime Gin

    Edible Landscape Citrus Trees

    Edible Landscape Citrus Trees

    Edible Landscape Citrus Trees

    Mani Skaria, Ph.D.

    Founder & CEO of US Citrus, LLC
    Professor Emeritus, Texas A&M University-Kingsville (
    www.uscitrus.com)

    Edible landscaping is the design, practice and the use of food-producing plants in the landscape. Fruit and nut producing trees are ideal for this purpose to bring the aesthetic aspects. Landscape architecture has is becoming a well-received area of specialization. Architects and local landscapers together would bring long-lasting beauty and edible fruit and nuts to your front and yard space. Please note that landscape design is not limited to trees only in addition, there can be berries, vines, vegetables, herbs, and flowers. The plants, designers, and landscapers together bring:

    i) Aesthetically pleasing surroundings to your home to enjoy with family and friends

    ii) iii) iv)

    A fresh food item to the table with control on pesticides used Quality time with family members, bees and birds
    Improve the quality of life

    v)
    fragrance not readily available

    Allows you to grow unusual varieties with color, shape, and

    1.Landscape citrus trees: Citrus is a family of diverse type of edible trees big size, small, spreading type, or erect. Our US Citrus nursery maintains over 150-different types of citrus. Your designer and your local landscaper would be additional resources for the best selection of citrus varieties that would fit your growing area. The following are some specialties of an ideal landscape citrus tree based on my experience and subject-matter expertise.

    2. Citrus tree size and shape. You do not want huge trees in your yard when planted for edible fruit. You should be able to pluck the fruit and to attend to pruning and tender loving care, without the use of a ladder. I am not against a ladder, but I pay more attention to safety aspects.

    Ideal height is 5-6 feet tall. You can always maintain the height and shape of the tree with proper pruning. When pruning, practice the art to get enough sunlight into the tree. Always keep sharp pruning shears. It can be used to cut off and physically remove leaves and small branches with pest or disease symptoms. Larger branches would require heavy duty tools.

    3. Citrus fruit type. Note that the family of citrus include the types: i) Limes and lemons
    ii) Oranges

    iii)
    iv)
    v)
    vi)
    vii)
    viii)
    ix) Citrons
    The above would cover the most widely-known types. Remember, there many selections under each type.

    Grapefruits and Pommelo

    The mandarins (Clementine, Satsuma, Kumquat and kumquat hybrids

    Calamondin (Chinese orange) Kaffir lime, Yuzu

    Australian finger lime

    4. Important considerations to be given.

    a) A citrus type that would give fruit year-round (Examples, are limes, lemons, kumquat)

    b)  Fruit not readily available in your neighborhood store

    c)  Exotic nature (Australian finger lime, new mandarins)

    d)  Colors (variegated fruit, pink flowers, variegated leaves)

    e)  Unique shape, color, and look (Australian finger lime, Chinotto orange, Bouquet de Fleurs sour)

    f) Ceremonial (religious ceremonies, example Citron for the Jewish community, Fingered citron for Chinese, Kumquat for the Chinese New Year, and lime for Indian hand washing after lunch/dinner)

    g) Cooking (Kaffir lime, Yuzu)

    f) Cocktails (Persian lime, Australian finger lime) Juice (limes, lemon, citron)

    5. Immediate gratification and planting size.

    The size of the plant at planting usually is a consideration for immediate gratification. Large size citrus plants in 25-gallon containers would bring an instant gratification and aesthetic beauty to the landscape if such plants are readily available. State and federal government agencies regulate citrus tree movement in this country. Therefore, check on the local sources for availability. Whether you are in a citrus producing state or not, always get your tree from a certified, credible source. Many nurseries in non-citrus producing states sell plants that are not required by state and federal inspections and certification. They sell citrus plants that do not meet stringent standards. Citrus is a perennial crop; it is expected to last decades – therefore, it’s worth investing time on researching the right source for your trees.

    Large container-grown trees would come with a higher price tag. A 4-5 feet tall citrus tree with flowers or fruit could easily coast from $150 to $350, depending on the variety, size, fruit set, and the type of decorative container. Alternatively, a citrus plant in a 5-gallon container would range from $55 to $95, depending on the variety, size, and fruit set. The price of an economically viable alternative as noted blow would be $30-$45 with micro-budded citrus from US Citrus nursery.

    Micro-budded citrus from US Citrus (uscitrus.com) is the best alternative one can get in this country to balance cost and time to fruit-set. The early-fruit-bearing attribute of micro- budded plants would be an economically viable alternative to immediate gratifications. A two-year-old, micro-budded lemon at the US Citrus orchard is shown below.

    2-Year-Old Persian Lime Tree

    6. Container-grown vs. Ground. You can grow citrus in containers – 25-gallon or above. Container trees can be moved around; however, the size and shape to be maintained. The ground is less maintenance. Many newer subdivisions in Texas have caliche-filled ground – it needs to be altered with topsoil and organic materials.

    Assorted Citrus Tree Photos