Problems with plants: the expert answers on plant diseases

Problems with plants: the expert answers on plant diseases



The section is dedicated to plant problems.If you wish to write to our agronomist in order to have an answer on an unclear situation or a difficulty concerning your plant, you must indicate:

  1. what plant it is;
  2. where it is located (inside the house, on the terrace, in the garden, etc.);
  3. the type of exposure (full sun, half-light, etc.);
  4. how long has it been in your possession;
  5. the general state of the plant;
  6. the frequency of watering;
  7. how often it is fertilized and the type of fertilizer used;
  8. any pesticide treatments carried out;
  9. the symptoms it presents and the parts of the plant affect;
  10. any foreign presence (insects or other).

If possible, send a photo, but in any case, take care to be very detailed in describing the overall state of the plant. The address to which everything is forwarded is: [email protected]

Your questions

Floriana di Portoscuso asks:

Hello very kind Floriana.

The plant in question of which you have attached the photos, is not oregano because the latter has narrower and more serrated leaves. So let's exclude oregano.

But I am also as sure as you that it comes to Lemon Grass (lemongrass), I am not if she has smelled the smell of the plant by lightly rubbing the leaves. It should smell like lemon.

The thing it should do is smell the leaves and see if it tastes like lemon or something else, because looking at it it looks more like a marjoram plant, because the Lemon Grass is a little different.

It should smell the leaves to have the definitive proof, otherwise it is another aromatic species.

Thanking you for your question, I cordially greet you.

Dr. Fabio Di Gioia
Specialized in the recovery and enhancement of ancient plant varieties

Plant diseases | The most frequent and targeted interventions

Fungi, parasites, bacteria, smog and pollution are the most frequent causes of plant diseases. We must recognize them in order to intervene in a targeted way

The plant diseases they are numerous, knowing how to distinguish them all is not easy: for this reason we have created this clear guide that helps to recognize the main ones plant diseases and understand how to intervene

The success and the success of the cultivation of plants and flowers it mostly depends on how we manage to keep them under control illnesses some plants they can be subject.

The most frequent plant diseases

Powdery mildew or white sore

L'powdery mildew or bad white it is a disease caused by a fungus that causes a whitish efflorescence on the leaves, calyxes and buds. It spreads quickly throughout the entire canopy causing it to dry out. It is necessary to counteract with sulfur-based fungicide treatments that solve the problem in a short time.


Scab: disease that causes roundish brown-purple spots on the leaves often accompanied by a pale halo. The leaves detach easily and, if the attack is strong, the plant can remain completely bare. To apply cupric fungicides and collect and eliminate fallen leaves.

Gray mold or botrytis

Gray mold or botrytis (botrytis). It's a cryptogam affecting tree plants and fruit. The affected parts (flowers and fruits) are subject to a progressive decay and desiccation with the appearance of a greyish mold. To prevent the onset of this disease, it is good to avoid stagnation of moisture and deal with Iprodione-based fungicides.

What parts of plants are prone to diseases?

Throughout the period of their life, plants are exposed to the action of pathological processes that affect them in the aerial part and in the roots causing lesions that, at times, compromise only the affected part, but more often act on the vitality and general performance of the plant.

Fungi, bacteria, insects, molluscs, viruses and the environment: many different causes

Many plant diseases can be effectively combated constantly monitoring the state of health of the plants themselves. Some plant diseases are due to the action of fungi is bacteria, others to the action of insects is phytophagous molluscs (beetles, lepidoptera, snails and slugs).

Many diseases are caused by virus (virosis, microplasmosis) and others due to the action of the environment (heat stroke, frosts, soil defects, etc.). It is important to be able to grasp the first symptoms in order to promptly intervene against the pathogenic elements in question.

Attention to diseased parts of plants must be carried out on all organs, including underground ones because often the disease can also be transmitted to nearby plants and flowers that are still healthy.

Diseases caused by pets

Phytophagous molluscs and other insects such as i rodilegno they conspicuously damage the plants of gardens and vegetable gardens, removing portions of tissues on which pathogens later settle.


The slug is a grain without a shell (snail) that feeds on the leaves of plants.


Snails are phytophagous molluscs that damage plants by gnawing portions of leaves.


Rodilegno attack trunks and branches of plants by digging tunnels and obstructing the circulation of sap.


Metcalfa is a small insect that densely colonizes the underside of leaves. It produces honeydew (sugar waste from metcalfa). On the honeydew, fungal diseases such as fumaggine.

Whitefly larvae

Whitefly larvae. They appear as small white flakes that gather on the underside of the leaves. They secrete a "honeydew" where a black fungus appears in a short time.

Larvae of hemiptera

Larvae of hemiptera covered with a white filament. With their bites they cause visible malformations on the leaves called "galls".

Cottony cochineal

Cottony cochineal on bougainvillea flowers. It looks like a small wad of white fluff that forms its nest on the lower pages of the leaves, on the trunk, in the semi-woody parts and in the buds.

The damage of moths

In the adult state they occur in the form of "butterflies", But they are already harmful in the state of larvae. They affect leaves and woody organs. Between the moths there are miners who insinuate themselves into the thickness of the leaves i rodilegno that dig tunnels and the nocturnes that carry out their phytophagous activity at night.


In the larval state they insinuate themselves into the woody organs by digging tunnels. Some species affect the leaves and the flowers by gnawing, by means of the elytra, the petals and removing showy parts of buds and leaves.

Red spider

It is a small parasite, red or yellow in color that deposits its eggs near the buds. It causes discoloration of the leaves which subsequently dry up. It is recognized for the characteristic formation of cobwebs.

The damage of grasshoppers

Grasshoppers belong to the order of Orthoptera which also includes crickets and locusts. They are "jumping" insects harmful to vegetation and crops. The mouth apparatus is equipped with robust denticulated mandibles with which they remove showy parts of leaves and flowers.

Bacterial diseases

The bacterial diseases of plants they are very dangerous, as they have a fast course and can kill the plant in a few days. The bacteria that cause rot attack the plant anywhere (leaves, roots, bulbs) to spread throughout the rest of the plant.

Most often these bacterial infections arise if there are gods stagnant water and very humid and unventilated environments and you can spread quickly between neighboring plants. It is necessary to take the plant, eliminate the infected parts and place it in a less humid and more ventilated environment.

Fungal diseases and molds

Compared to other diseases, they are a little easier to control, as they have a slower course. Molds can be found in both forms of rot that of drying of the aerial parts and are very common.

Most of the spots and specks that can be seen on the flowers are, instead, to be attributed to fungi, in particular to one, of the genus Bothritis, which causes desiccation of the tips and dark spots (and premature withering).


It's a cryptogam which forms dark spots on the upper and lower side of the leaves from which a reddish powder comes out. It weakens the plant and dries up the affected leaves, which must be burned as the spores of the fungus can remain in the soil from one season to the next. The affected parts are eliminated e a fungicide is applied at the first appearance of the disease.

Predict the climate and prevent plant diseases

The climate changes, the timing and the danger of plant adversities change and the consequent increase in the risk of diseases. A phenomenon that is having a notable effect on the dynamics of the formation of prices of fruit and vegetables: an evolution that can be prevented and managed?

The climate change influences several aspects of the biology of the host plant. The increase in temperature tends to anticipate the vegetative awakening of the crops, but also to accelerate the vegetative season leading to an early ripening. This has been noted for several years for pome fruit, stone fruit and vines. The constantly increasing concentration of carbon dioxide in the atmosphere can intensify photosynthesis with a consequent increase in vegetative mass and productivity. Positive effects that are nullified by the intensification of extreme atmospheric phenomena: concentrated and intense rainfall or, on the contrary, waves of drought.

The increase in average temperatures is also causing a greater frequency of the reproductive cycles of some parasites, a factor that can lead to a greater severity of epidemics with negative effects on agricultural production. The biological cycles of fruit and vegetable crops and their parasites are "re-tuning": what tools do producers have at their disposal to identify the right tuning? The use of the support systems of decisions (DSS) based on predictive mathematical models is a solution that can be advantageously applied to numerous diseases and adversities of fruit and vegetables and more. They ensure maximum effectiveness in short-term choices such as identifying the most appropriate period for treatments. Can they also be applied for broader strategic choices, such as crop choice or setting rotations for horticultural crops, or even for field management for fruit, in anticipation of a certain positive or negative commercial trend?

It is one of the great agricultural challenges, for now it can only be seen that the accuracy of the DSS is maximum in the short term, but decreases rapidly as time increases. Their constant and intelligent application, however, can make it possible to facilitate a district management of production, supporting the goal of identifying the most suitable areas and the most convenient crops even in a climate-changed context.

Riccardo Bugiani, of the Emilia-Romagna Region Phytosanitary Service, will deepen the theme on phytopathologies during the workshop "The price of fruit and vegetables: just a question of the market?" organized by Edagricole on 11 May next to Macfrut.

Garden Plants: Answer

Thank you for contacting us about your plant questions

from the garden, through the column of the Expert of

The study and research of plants to be placed in a garden must be done in such a way as to satisfy our aesthetic taste, perform an ornamental function and be easy to maintain. Based on your requests, we can suggest a Dichondra lawn

which does not need to be clipped and tolerates trampling very well, even if in winter it loses some of its aesthetic appearance they become green-brown in color.

As for the shrubs, the choice is a bit difficult if we have brightness limitations. Flowering perennials are very suitable, among these we can

indicate oleanders, jasmines, hydrangeas, mimosa, ancient roses, Forsythia, passionflower etc.,. Near the pond we can put moisture-loving plants such as bamboo, reed, Papito, Willow. The best advice is to contact an expert nurseryman in the area who has a nice catalog of plants that grow well in your reality, which is not subject to many diseases.

and that they are typical of the place to integrate easily with the local fauna.

Camelia - Camellia japonica

Genus of over 80 species of small evergreen, rustic trees and shrubs, native to India, China and Japan. The foliage is dark green, glossy, slightly leathery during.

Chrysanthemum - Chrysanthemum moriifolium

The name chrysanthemum usually indicates the flowers of the genus chrysanthemum that bloom in autumn. These are hybrid species, selected for the beauty or size of the flowers their d.

Sowing garden perennial flowers February

Finally winter is running out, and it is already time to get ready for spring and its splendid colors. Already this month we can begin to sow the perennial or annual seedlings from p.

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