• During cultivation

At the beginning of a localized attack of Oidium neolycopersici , it is advisable to carry out fungicidal treatments * ( e-phy ). We remind you that a treatment is only effective if it is applied at the right time, in the right dose, with sufficient volumes of mixture and application equipment suitable for the tomato. If you are faced with a well-established attack, it will often be difficult to control the course of the epidemic in the crop.

Some prophylactic measures to improve control of this yeast infection include:
- the elimination of plant debris from the plots and their environment, or their rapid and deep burial in the soil;
- destruction in the plot and its surroundings of weeds that can serve as relay plants for the parasitic fungus.

• Next crop

During the next crop, a number of additional preventive measures can be implemented to limit the risk of powdery mildew appearing.

In the open field, it will be desirable to carry out a crop rotation . This will not necessarily be long. We will choose the location of the future plot so that it is located in a fairly airy and sunny place. We will ensure a balanced manuring of the plants and we will ban the neighborhood of crops which already harbor O. neolycopersici .

In greenhouses, a crawl space will be made, as well as surface disinfection with one of the many disinfectants intended for this use (see the sheet Passaflora fulva ). Note that maintaining a humid climate would slow the progression of the disease. However, this measure involves some risks of promoting other aerial parasitic fungi of tomatoes.

In production areas and / or shelters where powdery mildew is more constant from one year to another, preventive treatments can be carried out with the products mentioned above.

The foliar application of several salts , such as CaCl ₂ , Ca (No ₃ ) ₂ and K ₂ HPO ₄ , would have made it possible to limit the number of leaf spots on tomato to levels comparable to those observed after treatments with sulfur.

Several resistances to O. neolycopersici are reported in the literature; they have been more or less exploited by breeders.

A resistance has been found in the wild species Lycopersicon hirsutum . This is controlled by incompletely dominant gene named " Oi-1 ", located on chromosome 6. A gene " Oi-3 " not genetically distinguishable from the previous one, would be located between the same two genetic markers on the same chromosome. Other wild species Lycopersicon have been shown to be resistant: L. pennellii (3 dominant additive genes), L. cheesmanii and L. parviflorum (polygenic resistance) (differences in resistance between accessions), L. chilense (1 partially dominant gene ), L. peruvianum (1 dominant gene, " Oi-4 "). Note that resistance to powdery mildew is often associated with a reduction in mycelial growth and sporulation of the fungus.


* Chemical control : As the number of pesticides available for a given use is constantly changing, we advise you to always confirm your choice by consulting the e-phy site of the Ministry of Agriculture and Fisheries which is an online catalog of plant protection products and their uses, fertilizers and growing media approved in France. This also applies to all biological products based on microorganisms or natural substances.