THE AGRONOMIST ANSWERS ON HOW TO GROW AND CARE FOR PLANTS
ONCE THE COCHINIGLIA HAS BEEN CURED, ARE THERE NATURAL REMEDIES TO PREVENT IT AND AS MUCH NATURAL REMEDIES USEFUL FOR THE SUBSEQUENT WELLBEING OF THE PLANT?
QUESTION FROM GIORGIO
Dear editorial staff,
I have read the answer to the problem of your reader Fabrizio on this page.
I am in the same conditions of attack by cochineal on a plant in the apartment, about 130cm high, six years old, in excellent health until early December 2006: in June it was moved to a new apartment, where it was fertilized and showed lively growth; it is located about 3 - 4 meters from a kitchen wall air intake, harmless in summer, but from where, with the first colds, a little cold air always comes. The plant is in a plastic pot with generic supermarket potting soil. In spring I would plan to replace the pot and soil as per your instructions.
The problem: this afternoon I went to a specialized shop (of the "Viridea" chain), asking for a systemic product, showing one of the leaves, on which - I had confirmation - was the cochineal. I was recommended a blend of oils (95% mineral, 5% Metalium) which I refused: the product is harmful to the aquatic environment (i.e. 70% of our planet), it is topical and non-systemic and therefore I do not it is of no use to resolve the difficult condition in which my Ficus Benjamina evidently finds itself. In addition, the plant is located in the apartment and distribute on it and therefore live with a product "harmful by contact and inhalation" does not seem prudent, if not absolutely necessary.
Searching among the systemic products, I have not found anything better and all are more or less harmful by inhalation, contact and almost always for the aquatic environment.
My question: the method that you recommend with cotton balls and denatured alcohol is much more valid and ecological (although I imagine that in the natural environment the scale insects are food for other insects), although very demanding in my case, but also it not systemic. Once the symptom has been cured and the cochineal removed, is it possible or advisable to administer natural elements useful for the well-being of the plant in pots? Or maybe my approach is not exactly phytological and once all the cochineal is superficially removed, the plant will resume its normal vegetative cycle by itself?
Thank you for your attention and above all for the excellent and very clear advice you gave your reader Fabrizio.
Dear Giorgio, thank you for your wonderful question. Sometimes it takes something other than how to treat a specific disease.
If I fully understand the question you ask me if, once the cochineal has been removed, there are natural elements to prevent it and if there are as many natural remedies to make the plant recover once the cochineal has been removed.
If this is your question, to the first question, my answer is no. There are no natural products that can prevent its appearance / reappearance.
Allow me a little digression. Let's talk for a moment about these insects that are so alarming and annoying.
Mealybugs are very useful insects in the food chain. For example, they are very useful to the ants that even raise and protect them to feed on their excrements. which in technical terms is called honeydew. Some species of ants even bring them to their nests to raise them or build shelters in plants to protect them. The honeydew they produce is very rich in nutritional elements that are different depending on the species of cochineals but in principle it is composed of sucrose or melezitose. To these add glucose, fructose, raffinose as well as numerous amino acids (aspartic, glutamic, asparagine, arginine, proline, valine, serine, threonine, etc.) vitamins that come directly from the plant sap.
I'll tell you something: in some desert locations in Asia Minor and the Near East (Iraq, the Sinai peninsula, etc.) the honeydew that some species of cochineals (and aphids) produce is so abundant on some tree plants (Tamarix isQuercus) which is collected in special containers to be used as an ingredient to make drinks and sweets (the so-called manna).
Now, what are these insects limited by in nature.
The scale insects are exposed to a very high mortality in nature during the nymph stage (to get to have the adult insect, the one you see, covered by that species of shield, they pass through 2/3 stages of juvenile forms, very vulnerable because not yet fully formed) both as a result of abiotic agents such as abundant rains, strong insolation, the chemical-physical nature of the soil and the quantity of water in the soil that can favor a greater or lesser circulation of the sap in the plant, the fertilizations that they can alter the osmotic pressure and therefore vary the concentration of the sap in the plant. For example, conditions of seasonal aridity, plants sensitive to cochineal can become resistant due to an increase in the concentration of the sap which makes it difficult if not impossible for the cochineals to absorb it with their thin stylets (the cochineals attach themselves with their stilettos to the plant to suck the sap ). In these situations, mortality becomes very high considering that it will be associated with high insolation (in technical terms this immunity that plants acquire is called phenoimmunity).
Among the biotic factors we can mention various pathogenic microorganisms such as some fungi (Sphaerostilbespp. is Cephalosporium spp.) which are active in hot-humid areas or some entomophagous insects such as, for example, coccinellid icoleoptera (ladybirds) or some calcidoid hymenoptera.
As you can see in nature they are well controlled but in our homes it is not possible to reproduce these conditions.
To keep them under control, the only things we can do is try to keep an environment that is not too humid and warm, which however must be compatible with the optimal conditions for our plant to vegetate well.
Once the scale insects have appeared, you must always keep them under control because with a "first pass" we can hardly eliminate them.
I fully agree with you that in the home, certain synthetic products are not appropriate to use them.
One thing I do for my ficus, in addition to constantly checking for mealybugs, is to shower it upside down. What does it mean. I take the plant, cover the earth with a plastic bag then take it from the bathtub and put it upside down and take a shower, taking care to pass my hand well in the points where it is most localized (the point of intersection between the leaf limb and petiole) so in addition to cleaning the leaves, I do a "preventive" action for any scale insects that can escape sight. It's not very scientific, but it works
When asked if there are natural remedies to make the plant resume once the cochineal has been removed, the answer is that apart from the usual cultivation treatments (considering that you have had this splendid plant with you for six years and that it is thriving), it is not necessary to do anything. other than precisely what is indicated above to try to completely eliminate the cochineal and prevent its further spread / proliferation.
The plant will recover, don't worry.
Dr. M. G. Davoli