Gave powdery mildew

The pepper, species

L., is among the 10 most consumed vegetables in the Brazilian market. In Brazil, in 2000, the area cultivated with peppers reached 13,1 thousand hectares. The average Brazilian productivity in the period from 1996 to 2000 had an average increase of 300%, going from 10,4 to 32,6 tons per hectare. Greenhouse cultivation and the use of hybrids have been responsible for the increase in productivity. Brazilian production is mainly concentrated in the states of São Paulo and Minas Gerais. São Paulo is the largest producer of peppers with 8.291 hectares, producing 70 thousand tons and generating 4.543 jobs.

There are numerous diseases that limit pepper production, such as powdery mildew, which has become one of the risk factors for cultivation in greenhouses, with losses of up to 80%.

Pepper powdery mildew was detected for the first time in Brazil in 1994 in the Federal District region. The causal agent of this disease is a fungus that presents an asexual stage called

and a sexual known as

. In Brazil, powdery mildew occurs only in the sexual phase.

Its incidence is increasingly increasing and endemic in the region of Brasília in the Federal District, Pilar do Sul, Elias Fausto, cities in the green belt, among others. Its greatest occurrence is in protected cultivation.

In addition to peppers, Oidiopsis taurica parasitizes other important crops such as tomatoes, cucumbers, okra, cotton, onions, artichokes, leeks, jilós, eggplants and also weeds such as Santa Maria grass (

) and the joá de capote (

).

Typical symptoms are characterized by the appearance of a white powdery mass on the underside of the leaves and, at the same time, yellowish spots appear on the corresponding upper side. It is during the flowering phase that the symptoms begin, intensifying during the fruiting period. The disease causes defoliation with consequent sunburn on the fruits, thus reducing the vegetative cycle, fruit quality and productivity.

The pathogen is spread essentially by wind and conditions such as low relative humidity, absence of water on the leaves, mild temperatures and shading, typical of the greenhouse environment, which favor its development.

Powdery mildew is considered a difficult disease to control; Fungicide applications are inefficient. Some cultural management measures can help in attempts to control, such as sprinkler irrigation, crop rotation with non-host crops, eradication of host weeds, in addition to the use of well-balanced fertilization.

Alternative products for controlling powdery mildew such as cow's milk, fermented dairy product (Yakult ®), salts such as monopotassium phosphate, sodium and potassium bicarbonate and silicates in different dosages have been tested, but they only minimize the damage.

The best way to control pepper powdery mildew is through the use of varieties with genetic resistance. There are reports in the literature that indicate that the best sources are in species of

e

, known as chili pepper and chili pepper.

In the species C. annuum, 100% of commercial pepper hybrids cultivated in Brazil and abroad are highly susceptible. The only source of resistance to pepper powdery mildew is known as the HV-12 variety and has already been evaluated both in Brazil in Piracicaba, SP, and Brasília, DF, and in Tunisia, Israel, France and Italy. It is a highly stable and desirable resistance to be used in crosses with peppers with high fruit quality.

At Esalq/USP, a genetic improvement program is being carried out to obtain lines and eventually hybrids of peppers and peppers resistant to powdery mildew. Hybrids resistant to powdery mildew with fruit quality and productivity associated with other resistance to pathogens is an unprecedented piece of cutting-edge research in Brazil and has great potential for the vegetable seed sector.

Pepper powdery mildew, caused by the fungus

, is the most destructive disease in protected cultivation, causing losses of up to 80% in production. Symptoms include the presence of a white powdery mass on the underside of the leaves, leaf fall and consequent sunburn on the fruits. The best control method is through the use of resistant varieties; 100% of commercial hybrids are highly susceptible. The only source of resistance is the HV-12 variety, but it has no commercial value. At Esalq/USP, a program is being conducted to obtain pepper lines and/or hybrids resistant to powdery mildew with fruit quality, which is cutting-edge research that has never been seen before in Brazil.

e

Esalq/USP, Piracicaba, SP.