Production of New Biopesticides from Cymbopogon citratus for the Control of Coffee Rust (Hemileia vastatrix) under Laboratory and Field Conditions.

One of the diseases with the greatest economic impact on coffee cultivation worldwide and particularly in Peru is coffee rust (Hemileia vastatrix). The search for sustainable control methods as disease management strategies in coffee cultivation is necessary. The objective of this research was to determine the effectiveness of five biopesticides based on lemon verbena (Cymbopogon citratus) for the control of rust applied in laboratory and field conditions to allow the recovery of coffee (Coffea arabica L. var. typica) in La Convención, Cusco, Peru. Five biopesticides (oil, macerate, infusion, hydrolate and Biol) and four concentrations (0, 15, 20 and 25%) were evaluated. The biopesticides were evaluated under laboratory conditions (light and dark) at different concentrations. The design used was completely randomized in a factorial scheme. The biopesticides were incorporated into the culture medium and inoculated with 400 uredospores of rust, and the germination percentage was evaluated. Under field conditions, the biopesticides at the same concentrations were evaluated for 4 weeks after application. Under these field conditions, the incidence, severity and area under the disease progress curve (AUDPC) of selected plants with a natural degree of infection were evaluated. In the laboratory, the results showed that all biopesticides were effective in reducing the germination of rust uredospores to values <1% of germination in relation to the control, which showed values of 61% and 75% in the light and dark, respectively, independent of the concentration used, with no significant differences between them. In the field, 25% oil promoted the best response with values <1% and 0% incidence and severity, respectively, in the first two weeks after application. The AUDPC for this same treatment showed values of 7 in relation to 1595 of the control. Cymbopogon citratus oil is an excellent biopesticide that can be used to control coffee rust.

First Report on the Genetic Diversity of Populations of Gossypium barbadense L. and Gossypium hirsutun L. in the Amazonian Native Communities, Cusco-Peru.

The genus Gossypium has important ethnobotanical and economic value for Amazonian Native Communities (A.N.C.). However, little research has been undertaken on the distribution and genetic diversity of cotton populations maintained in the Peruvian rainforest. This work aims to present the first report on the genetic diversity of Gossypium spp. populations in the A.N.C. of the province of La Convención, Cusco-Peru. The methodology was based on exploring, collecting, identifying, and characterizing the Gossypium populations present in the A.N.C. Twenty-six descriptors were evaluated (9 quantitative and 17 qualitative), and with this information, distribution, correlation, and principal component (PC) analyses were carried out. As a result, plants of two species [G. barbadense L. (44 samples) and G. hirsutum L. (19 samples)], one variety [G. barbadense var. brasiliensis (75 samples)], and three previously unidentified variations (9 samples) were identified. Altogether, 147 samples were collected. G. barbadense var. brasiliensis, which was always found in association with other economic crops within an altitude range of 338 to 1086 m, was the most predominant (51%), distributed in eleven A.N.C. and always in small plots (up to 2 ha). G. barbadense L. was cultivated between 397 and 1137 m of altitude in eight A.N.C. in plots of up to 3 ha in marginal lands. G. hirsutum L., with a smaller distribution (13%), was found between 334 and 497 m of altitude in only three communities; this species is cultivated in marginal areas throughout the year. The variability found for the first two PCs when considering the quantitative and qualitative descriptors was high (74.7%) and moderate (48.2%), respectively. When combining all the descriptors, the analysis showed that the first two PCs accounted for 51.8% of the total variability of the data. The PCs of the two types of data and their combination confirmed that the three populations found were grouped. The nine undefined samples were close to or intermediate between the described ones, showing that these samples may be the result of spontaneous crosses; as such, these samples need to be better evaluated with other tools for further definition. The information obtained shows that in the A.N.C. of Cusco-Peru, there is variability conserved by the inhabitants, who have been able to maintain and use these genotypes, even from their Amazonian indigenous ancestry, and the environment has been able to generate variability among the species, as will be highlighted in future works.