Answer: Tomatoes


three years ago, tomatoes suffered from a disease that turned them black in the lower extremity: last year I lost about 75% of the harvest. In agriculture they tell me it's a water supply problem; but I don't believe it, because tomatoes have always grown in the garden without problems, water or no water. Can anyone give me some indication?
Thanks, Giovanni

Answer: Tomatoes



Dear John,
We thank you for contacting us about the question about your tomato plants, through the "" expert's column.
The description that has made of the "disease" that has affected its tomatoes for three years is attributable to the PHYSIOPATHY DENOMINATED APPEAL MARCH.
The problem is attributable to nutritional problems among which the calcium element is the fundamental cause (lack in soil or soil with excessive acidity) in conjunction with water imbalances.
The physiopathy affects in particular the long fruit varieties, such as the San Marzano, cultivated both in greenhouses and in open fields.
It causes the fruits to have brown rot on the top of the berry when ripe.
The physiopathy presents the following course: it forms a blackish or brownish notch, slightly depressed, which subsequently extends also in depth.
The decomposing parts are covered with saprophilic fungal forms.
Causes
The main cause is the water imbalance and the lack of calcium in the fruits.
Therapy
In prevention we recommend adequate irrigation and foliar treatments with calcium-based products. Specifically for the apical rot of the tomato we recommend leaf treatments with a calcium-based product ...

Deepening: tomato diseases


The hobby cultivation of tomatoes is widespread in our country. It is a product of great importance in our kitchen and the access to freshly picked fruits guarantees an intense and sweet taste, difficult to find in those purchased. The Italian climate also guarantees, thanks to the help of greenhouses, a long period of cultivation and harvesting, giving great satisfaction to the fans.
However, it is true that it is a very demanding plant in many respects. In fact, regular irrigations, chiselling interventions and precise distribution of formulations are necessary for the prevention and the fight against pests, cryptogams, virosis and bacteriosis.
We will illustrate below the most frequent adversities and we will give indications on how to prevent them or eventually address them.

Aphids



Pathogens
Aphis gossypii, myzus persicae, macrosiphum euphorbiae
Symptoms and damage
The colonies settle on the apexes and on the back of the leaves, slowing down the growth and negatively affecting the general vigor of the plants. Following punctures of the mouthparts, curls and curls appear. They are also an important cause of virus transmission.
Prevention and care
avoid excessively nitrogenous fertilizations. At appearance it can be treated with products based on natural pyrethrins or pyrethroids. Alternatively you can also try infusions based on nettle, garlic or chilli

Red spider mite



Pathogen
Tetranychus urticae
Symptoms and damage
at first some point discolorations appear. On the back of the leaf you will notice red or black dots. Later the leaves will begin to curl and, in the last phases, they will be wrapped in a very fine spider web. The plant quickly loses vitality until it dies
Triggering factors
high temperatures and low humidity, cultivation in greenhouses
Prevention and treatment we avoid the massive use of insecticides. We intervene as soon as possible with specific acaricides or through integrated control (Phytoseiulus persimilis and Beauveria bassiana)

Thrips



Pathogen
Frankliniella occidentalis
Symptoms and damage
they feed on the sap by pricking the leaves and stems with the mouthparts. They cause a loss of vitality, silvery streaks and malformation of the fruits. However, the greatest danger is connected with the transmission of viruses.
Prevention and care
in the greenhouse it is possible to resort to the predatory insect Orius laevigatus. Anti-insect nets and blue-colored traps are also very useful. Spinosad, Beauveria bassiana (for biologics) or luferunon and acrinatrina in conventional methods are valid as phytotherapics.

Pomodoro rusty eriofide



Pathogen
Aculops lycopersici
Triggering factors
survives winter only in the South or in the greenhouse. Ideal temperature around 27 ° C with 30% humidity
Symptoms and damage
the base of the plant assumes bronze nuances extending then towards the apex and the fruits. The leaves curl up and become progressively bronzed to then become fragile and fall. The fruits remain small and show cracks.
Prevention and treatment in conventional agriculture are recommended first of all sulfur, which has an inhibitory action, secondly Propargite, Acrinatrina, Abamectin.

Green bug



Pathogen
Nezara viridula
Symptoms and damage
from July onwards the eggs appear on the back of the leaves. The advanced stages of development are very harmful due to the bites that operate on the fruits. Around them necrotic areas are formed and there is a complete lack of development, as well as an unpleasant taste. They also promote fungal and bacterial pathogens.
Prevention and care
at the first sightings use pyrethrins or pyrethroids.

Yellow tomato Nottua


Pathogen
Heliothis armigera, Spodoptera littoralis, Plusia gamma
Symptoms and damage
initially the larvae feed on the leaves and then enter the berries making them unusable
Prevention and care
application of insect nets in greenhouses, weed-carrier containment. Pesticides: Bacillus thuringensis var. Kurstaki, Indoxacarb, Lufenuron, Spinosad.

White fly



Pathogens
Trialeurodes vaporariorium Bemisia tabaci
Symptoms and damage
small light-colored flies, due to a waxy secretion that protects them. They live on the back of the leaves where, at temperatures above 20 ° C, they reproduce very quickly. They feed on sap and simultaneously produce a honeydew that dirty the plant and prevents photosynthesis (in addition to spreading mold). They are also vectors of viruses. Very common in greenhouses and in the Center-South.
Prevention and care
use of insect nets, preparation of yellow traps, reflective mulching (does not like strong light), washing with potassium soaps to remove the honeydew. In organic it is possible to rely on algae extracts, pyrethrins and Beauveria bassiana; in the conventional case instead neonicotinoids, buprofezin and pyridrine can be used.

Powdery mildew


Pathogens
Leivellula taurica
Symptoms and damage
on the front of the leaf appear yellow spots with shaded outline, on the back, in the same area, there is a white mold. It spreads from the bottom up.
Prevention and care
it spreads with temperatures around 23 ° and about 70% humidity. In greenhouses you need to ventilate, avoid too thick plants and take care of hygiene. It is prevented with sulfur, strobilurins or triazoles.

Mildew


Pathogens
Pythophthora infestans
Symptoms and damage
on the upper side of the leaves oily, irregular and bleached spots appear. A gray mold then develops. Later it spreads over the green berries where translucent areas appear which then evolve into brunettes. The fruits do not ripen and fall to the ground
Prevention and care
be careful in the case of temperatures between 10 and 25 ° C with very high humidity (and wet leaves). Ventilate the greenhouses, avoid wetting the leaves. Prevention through copper-based, treatment with strobilurins, dodine, thiocyanokinones.

Gray mold


Pathogens
Botrytis cinerea
Symptoms and damage
it settles through damaged fabrics during maintenance or at the ends. Chlorotic areas appear and then a gray mold. Then there is a necrotization of all the fabrics. The plant loses vigor and productivity.
Prevention and care
be careful with temperatures between 17 and 25 ° C, with humidity around 90%. Do not operate on wet days, ventilate greenhouses, avoid too dense plants and heavily nitrogenous fertilizations. As pesticides, anilino piramidine and strobilurine are indicated.

Alternaria


Pathogens
Alternaria spp
Symptoms and damage
on the whole plant appear round dark brown spots with concentric zones and a yellow halo, which become larger and converge.
Prevention and care
it diffuses from 2 ° C up to 37 ° C, with a high environmental humidity. It is prevented with cupric.

Septoria


Pathogens
Septoria lycopersici
Symptoms and damage
on the adult leaves appear necrotic spots of gray color and lead to the complete desiccation of the plant. It is preserved on the infected crop residues.
Prevention and care
it spreads between 15 and 28 ° C with high environmental humidity. Carry out extensive crop rotations, avoid water stagnation, use disinfected seeds, favor the aeration of greenhouses, do not implant too densely. Prevent with cupric.

Bacteria and viriosis


bacterial
Bacterial spotting, bacterial tapping, bacterial cancer, Tomato spotted wilt virus.
Pathogens Xanthomonas campestris, Pseudomonas syringae, Clavibacter michiganensis
Symptoms and damages on the leaves appear small brown spots, on the fruits then areas of about 1 cm blackish, with yellow halo. Cascola of flowers and fruits.
Prevention and care opt for resistant plants. Make large rotations, use uncontaminated water, moderate nitrogen and potassium fertilizations.
virosis
Tomato Yellow Leaf Curl Virus, Tomato Infection Clorotic Virus, Tomato Clostridium Virus, tomato bronzing virus, alfalfa mosaic: are transmitted by thrips, aphids and aleurodids. It is extremely important not to reproduce from infected material, counter the spread of vectors and eliminate the weeds on which they can winter. Use resistant varieties if available.

Tomatoes: Physiopathies



Apical rot
They are among the most frequent problems and usually occur between summer and autumn. Perine or elongated varieties are particularly sensitive. The cause is generally a calcium deficiency. In reality this may also be present in the soil, but some factors may inhibit its bioavailability. In particular they negatively affect a low environmental humidity with high temperatures, excessive presence of other elements (potassium, nitrogen), radical damage that prevents the absorption of water.
Splits
Cracks are just as common. The cause is generally an irregularity in irrigation, especially in the period of ripening and harvesting.
Sunstroke
Excessive heat and drop of leaves (also caused by cryptogam) can cause the appearance of wrinkled orange spots, with accentuated presence of lycopene. With suitable temperatures and humidity, rot can occur and lead to rot.
Floral waterfall
The causes can be many: from the sudden lowering of temperatures to unbalances in the humidity of the ground and air. In the greenhouse the cause may also be the lack of pollination.
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