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Premise
Assuming that in the fight against plant adversity "prevention is the best cure" and that "good nutrition is the best resource for disease resistance", we will examine in this second part the diseases that affect the drupaceae group.
In the agricultural group of the drupaceae are included the plants that produce fruit properly defined "drupe": the peach (nettarine-percoche), the plum, the apricot, the sweet and sour cherry (black cherry) and the almond.
They are fruit-bearing plants which, after a limited initial diffusion, then rapidly expanded thanks to the introduction of new selections such as dwarf nectarine peaches, early cherries or super-sized Chinese-Japanese plums.
These are reasons that have favored its cultural interest, sometimes extending its cultivation outside their ideal acclimatization zone, with particular reference to the requirements for cold (too much or too little) and for the difficulties (congenital or environmental) of their fertilization.
The success of the cultivation of stone fruit is therefore a mix of ideal conditions including the setting, the correct management of fertilization and defense, and, as for other crops, it is important to constantly monitor their status, in order to be able to intervene adequately, limit the spread of diseases and encourage proper development.
For this reason it is important to know how to recognize from the first symptoms the pathogens or the causes of the vegetative block that affect the various crops; to facilitate the identification of the adversities that affect the drupaceae, we group the adverse causes in tabular charts with the symptoms and the damage caused by the pathogens.
1) Non-parasitic diseases: nutritional or environmental
To exemplify the various diseases that damage drupaceae, the different causes can be grouped into: environmental, parasitic, fungal diseases, insect and animal damage.
All stone fruits, in order to be able to vegetate, flower and produce regularly, need neutral or sub-acid soil, rich in fertilizing elements, organic substances and suitable humidity.
The lack of a soil suitable for cultivation and lacking in nutrients causes a general deterioration of the plant, with manifestations of poor flowering, and therefore poor production, and leaf yellowing associated with various presence of pathogens.
The nutritional deficiencies negatively affect the whole physiology of the plant, first of all reducing their resistance to fight diseases, and, in the specific fruit sector, the damage is reflected on the economy due to lack of production, poor quality of the fruits and scarce shelf life of the same.
Drupaceae, like all plants, can manifest specific manifestations such as yellowing or leaf desiccation, scarce flowering and fruiting or insipid and deformed small fruits.
Depending on the type of nutrient that the plant lacks, the main causes are explained in the following table:
Symptom on the plant | Symptom on fruits | shortage |
Generalized discoloration of the plant and more pronounced yellowing in the basal areas. Stunted vegetation with poor flowering. | poor production and size | Nitrogen |
Bronze-purple coloration of the leaves, poor growth and poor flowering. | very slow or incomplete maturation, shortage in number of fruits and their preservation | Phosphorus |
The leaves take on a yellow-bluish color with desiccations that can bend the U-shaped flap. Poor lignification of the tissues and greater sensitivity to the cold. | small, acid fruits, poorly colored and with little sugar | Potassium |
The basal leaves turn yellow and dry in the central rib area. | strong fruit drop at maturity | Magnesium |
The leaves become opaque and fold down. The plates mainly dry on the margins and on the apex. | fruits that show cracks or deep fissures. The pulp turns brown in the hazel area. | Football |
Progressive yellowing from the apexes to the bottom of the plant with desiccation of the leaves. No or very poor flowering. | scarce and poor quality fruiting | Iron |
2) Parasitic aversion of drupaceae due to fungi
One of the most frequent problems with drupaceae is the proliferation of fungal or cryptogamic diseases, more commonly called "mold" due to the appearance of their fruiting that generally covers the plant attached.
These pathogens, if not fought for time, can quickly destroy the flowers and the fruits, therefore the production of the plants, and are favored by humid or rainy climatic situations, and they mostly afflict the drupaceae with nutritional deficiencies.
The manifestations are dependent on the plant and normally the various groups of pathogens prefer only certain organs and therefore the localization allows us to diagnose them.
The symptoms affecting the affected organs are various: they can be molds, rots, cancers, gums, holes, drying, the following table shows the symptoms and causes:
Symptom on the plant and on the fruits | Group pathological of mushrooms |
Sui stems and branches appear depressed red-purple areas, which then dry up with a split bark. | seccume of fruits, rameal cancer and fissures |
showy Bullous leaf malformations. Color of damaged leaves becomes white-red and they fall early. Even the fruits are very much deformed. | Bubble or Tafrina |
Up leaves, flowers and apices of the branches appear spots white felts. The flowers do not hatch or wither. Deformed fruits with white molds. | Powdery mildew or white mal |
Up leaves and flowers appear gray ashen mold, which subsequently dry up, also affecting the twigs. On the remaining fruits, they appear at maturity circle molds or may persist "mummified". | Molds of leaves, flowers and fruits |
on leaves appear red-purple spots in contour yellowed that later dry up leaving the pitted leaf. Cracks appear on the branches or notches that necrotize with gum leakage or resins. On the fruits appear brownish-black specks . | maculature foliar or Corineum |
Abnormal presence of twisted twigs and close internodes. The leaves on these branches are small and chlorotic. | Scopazzi |
Symptom on the plant and on the fruits | GUY OF INSECT |
They cover all the young parts of the plant and carry it rapid wilting due to sap subtraction. They produce honeydew with "fumaggini", they transmit virosis. The damaged fruits are deformed and underdeveloped. | Aphids or lice |
I'm larvae of hymenoptera of white or yellow color, which they eat leaves, flowers or young fruits. | Tentredini |
They suck the sap like aphids, they differ in being almost motionless and living protected by waxed badges white, yellow or red. They stare at each other leaves branches, fruits. These insects also produce "Fumaggini" due to honeydew. | Scale insects |
I'm microlepidoptera larvae that "undermine" the area green of the leaf leaving the cuticle intact. The leaves dry and fall. | Larvae of lepidopteran miners |
I'm caterpillars or larvae of butterflies that they destroy with the their erosions either the young shoots or kiss i fruits in the process of formation causing their precociousness fall. | Moth, Cydia or Anarsia |
I'm sucking butterflies that prick young leaves or buds. The affected organs present curl up with silvery colors | leafhoppers |
fruits that at maturity they appear flaccid due of the presence within a whitish larva who eats the pulp. | MOSCOW OF FRUITS |
I'm tiny spiders that they cause with their bites on the yellowing leaves that later dry up totally. They are very mobile and when they attack massively the plant also produce small cobwebs | Mites or red or yellow spiders |
