How to treat black scale on olive trees
Remove Scale Insects On Olive Trees In Pots
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Scale insects, in particular brown soft scale, is a common problem on olive trees in pots and can be one of the most challenging tree pest problems to control.
Scale attacks olive trees leaves and stems by attaching to and sucking tree sap (i.e. lifeblood of a tree) from new, tender growth. As a result, scale insects on olive trees in pots can cause leaves to yellow or wilt and the tree to weaken and become stressed. Overall, the growth cycle of the olive tree may be adversely affected, and the scale pests could certainly cause weakened flower or fruit production. But in general, complete loss of the olive tree is rare unless the tree is not cared for at all and pest infestation is heavy.
So how do you get rid of scale insects on olive trees in pots? Firstly, you should clean your olive tree with water. Next, take a cotton ball and wipe away the scale insects. Then, spray the olive tree with insecticidal soap to remove the scale remains. Repeat this least-toxic method in a week’s time.Scale insect is one of the most common pests on an olive tree. Don’t panic, it is not harmful as long as you treat and recover the tree
In addition, we have more useful information on how to identify scale on your potted olive tree and how to remove it here in this article. Let us take a look at least-toxic methods of scale control and best practices.
|Areas affected||Trunks, branches, foliage, and stems of olive trees, or olive fruit|
|Appearance||Brown, black scales, or shell-like bumps on olive tree stems and the underside of leaves|
|Main symptoms||Scale on stems and leaves, or olive fruit, sooty mold on foliage|
|Timing||Scale appears year-round|
What are the Symptoms of Your Olive Tree Attacked by Scale?
Firstly, you must identify the pest correctly prior to applying a treatment. These are the most common scale infestation symptoms:
- Scale Appearance
Scales or shell-like bumps on olive tree stems and the underside of leaves. These are the outer coverings of scale insects, usually brown or black color. In general, there are two categories of scale, and here is how to identify them:
- Soft Scale Insects (easy to control)
Appear as small, waxy, or crusty bumps on leaves, stems, and sometimes olive fruit. Secrete a waxy substance that is part of the body. The soft scale is able to move short distances and produce enormous amounts of honeydew.
- Armored (hard) Scale Insects (very difficult to control)
Secrete a hard protective covering (0.1 inches = 0.3 cm long) over themselves, which is not attached to the body. The hard scale lives and feeds under this sphere-shaped shield and does not move around the olive tree. They do not produce honeydew.
The size of scale insects ranges from 0.03 to 0.4 inch (1mm to 1 cm) in diameter.
- Honeydew Extraction
As scale feeds on the plant, the insects excrete a sweet, sticky substance called honeydew that settles on surrounding tree parts and surfaces near the plant. If your olive tree is indoors, the floor or shelf under the potted plant may become very sticky. Another disadvantage of the honeydew produced by scale is that it causes another fungal disease named sooty mold.
- Eggs Production
In some cases, scale insects can produce white, waxy egg masses on the undersides of olive tree leaves or stems, trunk, or even a pot. As well, the scale may deposit their eggs under a covering of white waxy fibres, especially in early summer.This soft scale insect leaves honeydew like traces, consume olive tree nutrients, and produces more eggs under the leaves
How to Get Rid Of Scale Insects on Olive Trees in Pots?
After you have identified that your potted olive tree has been infested by scale insect, then is time to take some actions and get rid of this pest. And here we have 2 scenarios on how to get rid of scale insects on olive trees in pots:1 scenario – scale numbers are low
- Clean your olive tree by using a soft flow of water from a garden hose. And rinse the honeydew off the leaves, stems, trunk, and container. Do this in the backyard, sidewalk, or driveway, away from other plants as not to spread pest around.
- Allow for the olive tree foliage to dry naturally.
- Then observe the tree and you should rub or pick off the remains of scale by hand.
- As well, you can take a cotton ball soaked in alcohol or neem oil and gently wipe away the scale insects one by one. It is important to wipe both the upper and undersides of olive tree leaves as well as all of the stems and trunk. Change cotton balls frequently. We recommend wearing rubber or vinyl gloves while going through this procedure.
- For further pest protection, use organic insecticidal soap or d- Limonene or lemony water and thoroughly spray the entire olive tree and a pot by following the manufacture’s instructions. Make sure your spray covers all parts of the potted olive tree to suffocate any scale insects and eggs that you have missed. Bear in mind, these products have very little persistence in the pest affected environment, so several applications during egg-hatching will be required for effective control.
- Wait until the potted olive tree is completely air-dry before moving it back to its growing location.
- Fertilize to boost the growth of your olive tree.
- Prune and dispose of heavily infested olive tree branches, twigs, and leaves.
- Use organic non-toxic pure Bliss neem oil. This concentrated spray is approved for organic use and offers multiple modes of action, making it almost impossible for scale and other pest resistance to develop. Best of all, such neem oil doesn’t poison honey bees and many other beneficial insects.
- As well, you can use horticultural oils for organic gardening and other safe, oil-based insecticides by suffocating insects and will control all pest stages, including adults which are protected from most other insecticides by their shield coverings.
- If nothing works as per the above, fast effect systemic insecticide applications should be used as a last resort. Comparing with synthetic chemicals, these natural pesticides have less harmful side effects and break down more quickly in the environment.
- Fertilize your olive tree to boost its growth (you may want to check our article about olive tree fertilization).
Above: this is a heavy infestation of scale insects on olive trees
If your potted dwarf olive tree grows outdoors, let the predators such as ladybugs or lacewings, or small parasitic wasps visit your tree. They are the natural not harmful controllers of scale insects on olive trees in pots and other plants.
Things You May Need to Fight Scale
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- Garden hose
- Cotton ball
- Vinyl gloves
- Neem oil
- Insecticidal soap
- Horticultural oils
- Insecticide applications
These steps may sound like an overwhelming task, and depending on the size of your olive tree in the pot, it may be a bit of a challenge. However, if you follow the methods above will give you the best chance of eliminating the existing scale insects and preventing more from attacking your plant.
Hope this article was helpful for you and now you have all the information to get rid of scale insects on your olive trees in pots. Let us know how it went in comments or in our recently created Facebook community.
As for prevention purposes, you can spray your potted olive tree with oil or soap early in summer. Also, if you ensure regular care and maintenance of your olive tree, you may be able to spot the scale development very early and quickly remove the insects by just using your cotton ball and rubbing alcohol.Relevant Posts
- How to Revive Olive Tree and Bring Back to Life?
- Problems with Olive Trees in Pots & Solutions
- Olive Trees in Pots Winter Care
- 10 Steps for Moving Olive Trees Indoors
Are You Looking to Buy an Olive Tree?
If you are looking to add more potted trees or other plants to your orchard, or if you like to replace a neglected olive tree, the best places to get them are your local nursery or an online nursery.
One of the most reliable and the world's largest online nurseries is Fast Growing Trees. They deliver fast, neat, and healthy plants backed with a 30-day guarantee.
Black Olive Scale Explained - Amanda Bailey on Olives by The Olive Centre
|Occasionally a sap-sucking insect known as Brown or Black Olive Scale will be seen on olive trees. It is rarely a problem if the trees are in good health. We usually only spray our mature trees for scale every two to three years and only then if they need it. However, certain areas of Australia are more prone to the scale. |
The adult females are very easy to recognise on the olive tree stems. They are dome shaped, dark brown to black in colour, and about the size of a match head.
The tiny eggs laid under the female, look like piles of very fine sand. Mainly during the summer, these eggs hatch into tiny, six-legged, cream coloured ‘crawlers’. The crawlers move up the stems and usually settle along the veins of young leaves. At this stage they don’t have the impervious shell of the adult and can usually be killed with one or two applications of white oil about two weeks apart. White oil should be used only as directed on the label by the manufacturers (and by your agricultural department) and never during the hot part of the day. It puts an oil film over the young ‘crawler’ and suffocates it. If applied in the hot part of the day it also stops the leaves from breathing properly and can be detrimental to the tree. The White oil application will also tend to rid the tree of ‘sooty mould’ as discussed soon.
If the crawlers are allowed to live, they will moult after about one month and then migrate to the young stems and twigs of the tree. Here they will mature and lay more eggs and their protective brown shells will be impervious to white oil. Squash the scale between your fingers to see if it is alive. If it is alive, then your fingers will be wet from the juices squeezed out. If it is dead then your fingers will be dry and dusty.
Bad infestations of live mature scale may need spraying with an insecticide such as Supracide. (Important: See note regarding “Treatment”) In Greece, Supracide is the main spray used for most olive problems. Once again, check with your local agricultural chemical supplier and the product label, for directions.
Probably the damage done by the scale itself to the tough olive tree is negligible compared with what happens next.
As the scale feeds, the ‘manure’ they excrete is a sweet, sticky, ‘honeydew’. This excreted sticky liquid can finally cover the leaves of the entire tree. A fungus known as sooty mould feeds on this food and multiplies until the entire tree may be covered with the black sooty mould. This is where the real problem lies.
The leaves are coated with the black deposit, so the sun’s light can’t penetrate the leaves properly. Therefore photosynthesis can’t take place efficiently. Therefore, ‘root producing’ food is not manufactured in the leaf. Therefore roots don’t develop properly. Therefore the poor root system can’t collect enough food and water from the soil to send up to produce more leaves, which in turn will produce more root. Once the vicious cycle begins, a stunted and unhealthy tree with poor crops is the result.
To make the problem worse, sweet ‘honeydew’ on the leaves also attracts large numbers of ants. It appears that as the ants constantly move over the scale, they frighten away the small wasp parasites which in normal cases would keep the scale under control.
Above: Adult scale on the underside of olive leaves
Above: overturned scale with orange crawlers showing.
Above: An olive branch covered in sooty mould.
Above: Closeup of sooty mould on olive leaf.
The good news is that healthy olive trees don’t get the scale, sooty mould and ant infestation to any great extent. More good news is that heavily infested trees are easily fixed.
Normally, one thorough spraying of the entire tree and soil below with a systemic insecticide will be adequate. Nevertheless, to be sure, a second spray about two weeks later may be worthwhile.
Now, if there is no more live scale, there is no more eating, therefore no more ‘honeydew’ excreta, therefore no more sooty mould and ants. Over a period of time the dead sooty mould deposit will peel off the leaves from exposure to the rain, wind and sun. The green leaf surface will be exposed and growth will continue as normal. Treat the tree to an occasional feeding of Seagold fertilizer/mulch and foliar application and some water and watch its health come back.SCIENTIFIC NAME: Saissetia oleaeDESCRIPTION OF THE PEST
Black scale adult females are about 0.20 inch (about the size of a match head) in diameter. They are dark brown or black with a prominent H-shaped ridge on the back. Young scales are yellow to orange crawlers and are found on leaves and twigs of the tree. Often, a hand lens is needed to detect the crawlers. Black scale usually has one generation per year in interior valley olive growing districts. In cooler, coastal regions multiple generations occur. Black scale prefers dense unpruned portions of trees. Open, airy trees rarely support populations of black scale.DAMAGE
Young black scale excretes a sticky, shiny honeydew on leaves of infested trees. At first, affected trees and leaves glisten and then become sooty and black in appearance as sooty mould fungus grows on the honeydew. Infestations reduce vigour and productivity of the tree. Continued feeding causes defoliation that reduces the bloom in the following year. Olive pickers are reluctant to pick olive fruits covered with honeydew and sooty mould.CULTURAL CONTROL
Pruning to provide open, airy trees discourages black scale infestation and is preferred to chemical treatment.BIOLOGICAL CONTROL
A number of parasites attack the black scale, the most common are Metaphycus helvolus, Metaphycus bartletti, and Scutellista cyanea. These parasites, combined with proper pruning, provide sufficient control in northern and coastal orchards. In other regions, biological control is often ineffective because the black scale’s development pattern hampers parasite establishment.ORGANICALLY ACCEPTABLE METHODS
Cultural and biological control and oil sprays. Organic pyrethrum sprays like Pyganic ( Pybo is no longer organically certified).WHEN TO TREAT
If infestations are resulting in honeydew, treat the crawlers. In interior valleys, delay treatment until hatching is complete and crawlers have left protection of the old female body. Once crawlers have completely emerged, a treatment can effectively be made in summer, fall or winter provided the scales have not developed into the rubber stage (later second instar, which are dark, mottled grey, and leathery, with a clear H-shaped ridge on the back).TREATMENT
Due to the chemical nature of the treatments, Please check with your agricultural chemical supplier as to the suitability, application and safety precautions of your chosen scale treatment for olives. Some growers have used Summer or Petroleum Oil and Supracide. Californian olive growers use Oil Emulsions, Diazinon 50WP, Methidathion and Carbaryl. The use of chemicals reduces the microbial population in your soil and can inhibit the uptake of certain nutrients to your trees. Harmful residues of chemicals can also build up in your soil structure.
A new product Admiral has become available which acts as an insect growth regulator rather than a kill-on-contact pesticide, it has been quite effective and like any treatment of scale; timing is essential. Ants can be controlled with an Ant Bait suitable for Horticultural use. We suggest Distance Plus Ant Bait.References
“Olives – Pest Management Guidelines” (UCPMG Publication 8, 1994). These guidelines cover the major olive problems found in Australia and California and are available for free from their website http://www.ipm.ucdavis.edu/PMG/selectnewpest.olives.html . (The information comes from California so all references to places, seasons, months and treatments are Californian). If you have any questions, please contact The Olive Centre, PH: 07 4696 9845, FAX: 07 4696 9914, Email: [email protected]
- Admiral Advance
- Distance Plus Ant Bait
Black plaque on the leaves - how to treat? — FloweryVale.ru
Leaves are covered with black sooty coating which quickly forms a crust. This is a very common disease. It is sometimes called niello due to its resemblance to soot. It is caused by numerous fungi: Cladosporium, Torula, Triposporlum.
These fungi develop on weakened plants affected by aphids, thrips, mealybugs, whiteflies, scale insects. The honeydew of these sucking insects becomes fertile ground for sooty plaque.
By themselves, sooty fungi do not cause much harm to the plant. The black coating on the leaves interferes with the normal process of photosynthesis, and therefore the growth of the plant. The entire leaf is gradually covered with a kind of black powder that forms a crust, while worsening the appearance of the plant.
Plants most susceptible to soot: azaleas, citrus fruits, dieffenbachias, camellias and palms, rubbery ficus. Fungicides are useless against black plaque. Need to fight insects leaving a sticky residue.
Washing all leaves one by one will help to get rid of black plaque on indoor plants. Wash the leaves with an alcohol solution to remove the sticky dew of insects. You can use fresh beer. In addition, it gives shine to the leaves. You can give the plant a warm shower by covering it with an earthen blanket.
Treat large plants (including trees) with copper-soap solution (5 g of copper sulfate and 150 g of soap per 10 liters of water). You can treat trees with a solution of Bordeaux liquid or copper oxychloride, as in the case of scab. Avoid excessive soil moisture and thin out dense canopy.
See also: A white velvety coating has appeared on the leaves. What to do?
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Pests of olive trees: symptoms and treatment
The olive tree is a fruit tree that does not have many enemies. It is a tree that grows at its own pace, that is, neither too fast nor too slow; although it is true that in the first years of life he does this at a somewhat faster rate than he ever matures. This is a property it shares with other trees and is nothing more than a survival strategy.
And the fact is that from the moment the seeds germinate until the plant gets stronger, time passes, and during these months (or years) microorganisms and insects appear that will take advantage of any opportunity to harm them. But in particular What are the pests of the olive tree? Are you safe when you reach adulthood?
Not really. All fruit trees, since they produce edible fruits (not only for humans, but for many other animals and/or insects), may end up being preyed upon by those insects that reproduce rapidly. Some, if they are few, the only thing they can do is perhaps damage some leaves or fruits, but since they reproduce very quickly and in large numbers, we will have to take measures to protect them.
So, let's see what the pests of olive wood are and what we should do to save it safe:
- 1 Satter Pillow Chervets
- 3 Olive moth
- 3.1 Treatment
- 4 Olive fly
- 4.1 Treatment
Image - Wikimedia / Toby Hudson
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The mealybug is a pest that affects many agricultural crops, including the olive tree. The species that cause damage are Cyssetia oleifera . Unlike other species of mealybugs, this one is dark in color (rather than white) and is 2-6 millimeters long. You will find it in green branches and leaves where it feeds. . At the same time, it secretes molasses, which attracts black or sooty fungus, which causes the leaves to turn blackish.
Especially it appears in places with high humidity, as well as after rains. It is important to carry out preventive treatments if there have already been olive trees with this problem so that it is protected.
There are several highly recommended remedies for mealybugs:
- Natural or environmental insecticides : diatomaceous earth, potassium soap, neem oil.
- Specific insecticides : i.e. chemical against mealybugs. For example, cypermethrin is a substance that eliminates them.
For greasy, natural fungicides containing sulfur can be used.
Image - Wikimedia/Donald Hoburn
Eusophera, also known as drill, olive tree worm, or olive tree worm, is a pest whose scientific name is Eusophera penguinus . It is a small Lepidoptera, less than two centimeters long, with light brown wing stripes and darker brown stripes. In the larval stage, it digs round passages in branches, as well as in young trunks.
You have to be very careful when pruning, as it is a very common pest for trimmed olive trees. Therefore, it is worth applying a healing paste to the wounds so that the females cannot lay eggs.
In addition to what we just discussed about pruning, When symptoms appear, the olive tree can be treated with approved insecticides such as:
- Montana Wax 20%
- Cyflufenamid 5.13%
- Clopyralid 60%
- Deltamethrin 10%
Image - Wikimedia/Giancarlo Dessi
In addition to being known as the olive moth, the term "prayer" is also commonly used to refer to it. Scientists call it Pray oleae . It is one of the most common and harmful pests of the olive tree, since it goes through three generations, affecting different parts of the tree: the first on the leaves, the second on the flowers, and the third on the fruit.
The adult is a greyish Lepidoptera (butterfly) about 1.3 cm in size; the caterpillar, on the other hand, reaches 8 millimeters, but its color changes depending on the diet.
To control and/or eradicate olive moth plague you must use approved phytosanitary products. In Spain it is:
- Rapeseed oil 44%
- Alkyl Polyglycol 20%
- Azoxystrobin 25%
- Bacillus thuringiensis Kurstaki 32%
Image - Wikimedia / Giancarlo Dessi
La olive fly, whose scientific name is Bactrocera oleae , is a spring plague. Adult females lay their eggs in fruits, that is, in olives, so that after hatching they are no longer edible to humans. The simplest symptom is brown spots or even small holes that appear on the fruit.
It goes through four stages: egg, larva, pupa and adult. The latter is about 4-5 millimeters long, has transparent wings, and its body is reddish brown or orange; the mature larva is whitish, elongated, 6-7 millimeters long.
If your olive tree has this pest, you must treat it with approved insecticides. In Spain, some :
- Alpha cypermethrin 10%
- Sulfur 72% or 80%
- Bentazon 87%
- Bifenox 48%
IMPORTANT NOTE: In order to use some of the insecticides we mentioned, you will need a phytosanitary vendor card. If you don't have one, and for your own safety, we advise you to have someone who does have it handle your tree. Another option is to sign up for a course which is short (about two days) and can be very helpful if you need to use chemical insecticides. Contact your local council for more information.