Protection methods 

• During cultivation
  

If you are confronted with attacks of Thanatephorus cucumeris ( Rhizoctonia solani ) in the nursery, we advise you to eliminate diseased plants and those nearby.

Currently no fungicide is approved for this use on zucchini and squash in France ( e-phy ) (general treatment e-phy ).

The climate should be controlled as much as possible in order to avoid excess humidity and temperature . The irrigation of the plants must be optimal. In no case excessive, it must allow a good wiping of the substrate.

Attacks on adult plants are not normally too damaging on Cucurbita spp. and therefore do not require special measures. In any case, it is too late to intervene, moreover the zucchini does not easily reform adventitious roots.

In order to try to keep the plants alive as long as possible, you should:
- to butter them in order to try all the same to generate adventitious roots which can replace the old damaged roots;
- to bathe them during the hottest periods of the day to avoid excessive and uncompensated evaporation, leading to wilting, drying out and death of the plants;
- monitor carefully the irrigation . Indeed, if the plants wither, it is not necessarily linked to a lack of water, but rather to root alterations due to R. solani , alone or in complex with other soil-borne pests.

In all cases, plant debris, diseased plants and fruits will be removed during and at the end of cultivation.

• Next crop

To avoid introducing this parasitic fungus into your farm, it will be essential to use a healthy substrate and quality plants . Plants produced in mini-clods or on other substrates should not be placed directly on the ground, especially if it has not been disinfected; a plastic film will have to insulate them.

In heavily contaminated soils, disinfection of the soil with a fumigant will be considered ( e-phy ). The active ingredients conventionally used (metam-sodium, dazomet ) and the vapor are effective with regard to T. cucumeris . Particular care should be taken to avoid re-infestation of the soil after treatment.

In production areas where it is possible, solar disinfection of the soil will be carried out. The soil to be disinfected should be carefully prepared and moistened, then covered with a polyethylene film 35 to 50 µm thick, held in place for at least one month at a very sunny period of the year. This economical, efficient method makes it possible to get rid of this superficial colonizing fungus from the soil.

Of course, the agro-cultural measures recommended previously during cultivation must be implemented. In addition, heavy and wet soils will be drained. The rotation crop will be made with cereals, sweet corn, forage grasses and onions. The soil should be mulched to prevent the fruits in particular from coming into contact with the soil and the water sometimes present on the surface. In addition, it will in some cases promote better aeration of the crowns of plants and vegetation. The fertilization will be balanced, in no case too low in nitrogen.

There appear to be differences in sensitivity to T. cucumeris between Curcubitaceae.

Several antagonist microorganisms have been tested to control T. cucumeris : Bacillus lentimorbus, B. subtilis, Burkholderia cepiacea, Pseudomonas aeruginosa, P. fluorescens, Streptomyces sp., Paenibacillus lentimorbus, Pochonia chlamydosporia, Chaetomium globosum, Glomus mosseum, Trichoderma viride, T. harzianum, T. koningii . Although promising in some cases, the use of these microorganisms is not yet sufficiently reliable to be able to recommend them in the field.

Note that Gliocladium catenulatum is currently authorized for soil treatment / Rhizoctonia ( e-phy ) use.

Let us also point out other unconventional solutions which have revealed some potential with regard to this fungus: amendments based on Azadirachta indica in particular, essential oils of Callistemon lanceolatus and Ocimum canum , antioxidants .

* 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 products phytopharmaceuticals and their uses, fertilizers and growing media approved in France. This also applies to all biological products based on microorganisms or natural substances.