**3.4 Colony characterization of** *Fusarium* **sp.**

**Strain EV1r.** The growth of *Fusarium* sp. EV1r in PDA medium developed a fastgrowing colony (4 days) with beige color (**Figure 3A**). The texture of the colonial surface was cottony presenting a smooth and irregular margin. On the other hand, the development of the strain e EV1r in corn flour agar (CA) developed a fastgrowing white colony with a radial pattern and regular margin with a powdery texture (**Figure 3B**). In addition, the EV1r strain was also grown in SNA medium showing rapid growth (5 days) with a white front and back color with the presence of mycelium (**Figure 3C**).

**Strain H1Zra.** The growth of *Fusarium* sp. strain H1Zra in PDA medium developed a fast-growing colony (5 days) showing white color on both sides (**Figure 4A**). The texture of the colonial surface was cottony with the presence of aerial mycelium and irregular margins. On the other hand, the development of the *Fusarium* H1Zra strain on corn flour agar (CA) developed a fast-growing colony with white color, radial pattern, and regular margin. A velvety texture with the absence of aerial mycelium (**Figure 4B**) was also observed. In SNA (Synthetic Nutrient-Poor Agar) medium, the H1Zra strain showed slow growth (8 days) with an opaque colony and little mycelial development (**Figure 4C**).

**Strain H1Zrb.** The growth of *Fusarium* sp. H1Zrb in PDA medium developed a fast-growing colony (4 days) of white color with a slight yellow color in the periphery of the colony (**Figure 5A**). The texture of the colonial surface was velvety with the presence of mycelium with a regular margin. The development of the H1Zrb strain on corn flour agar (CA) developed a fast-growing white colony with a radial pattern and regular margin with a velvety and powdery texture with the absence

#### **Figure 3.**

*Colony morphology study in* Fusarium *sp. strain EV1r. Growth media: A) potato dextrose agar-PDA, B) corn flour agar-CA, and C) special low-nutrient agar-SNA.*

**Figure 4.** *Colony morphology study in* Fusarium *HIZra strain. Growth media: A) PDA B) CA C) SNA.*

**Figure 5.** *Colony morphology study in Fusarium sp. strain HIZrb. Growth media: A) PDA B) CA C) SNA.*

of aerial mycelium (**Figure 5B**). In SNA medium, the *Fusarium* sp. H1Zrb strain showed rapid growth with an opaque white colony with low mycelium development (**Figure 5C**).

**Strain K4Zr.** The growth of *Fusarium* sp. K4Zr in PDA medium developed a fastgrowing white colony with the presence of growth rings (**Figure 6A**). The texture of the colonial surface is cottony with the presence of aerial mycelium with a regular margin. The development of the K4Zr strain on corn flour agar (CA) developed a rapidly growing white colony with a radial pattern and regular margin with a cottony texture with the presence of floccose mycelium (**Figure 6B**). On the other hand, in the SNA medium, the K4Zr strain showed slow-growth with an opaque white colony with a flat texture with little development of mycelium (**Figure 6C**).

**Strain K5Zr.** The *Fusarium* sp. strain K5Zr inoculated on PDA medium developed a slow-growth colony (8 days) showing opaque yellow color, with a floral pattern and irregular margin (**Figure 7A**). The texture of the colonial surface was creamy with the absence of aerial mycelium. The development of the K5Zr strain on corn flour agar (CA) developed a rapidly growing white colony with a radial pattern and regular margin with a cottony texture and abundant aerial mycelium (**Figure 7B**). In the SNA medium, the K5Zr strain showed restricted and diffuse growth with an opaque white colony and irregular margin (**Figure 7C**).

**Strain C3WC.** The growth of *Fusarium* sp. strain C3WC in PDA medium developed a slow-growing colony (4 days) of white color, with regular pattern and margins (**Figure 8A**). The texture of the colonial surface was flat and velvety with the absence of aerial mycelium. On the other hand, the development of the C3WC strain on corn flour agar (CA) developed a colony of white color with a slight brownish color of rapid growth. Radial pattern and regular margin with a cottony

*Importance of the Natural Incidence of the* Fusarium *Genus in Food Crops Established… DOI: http://dx.doi.org/10.5772/intechopen.100595*

#### **Figure 7.**

*Colony morphology study in Fusarium sp. strain K5Zr. Growth media: A) PDA B) CA C) SNA.*

**Figure 8.** *Colony morphology study in Fusarium sp. strain C3WC. Growth media: A) PDA B) CA C) SNA.*

texture and abundant aerial mycelium were also observed (**Figure 8B**). In the SNA medium, the C3WC strain showed a slow-growth colony with an opaque white color and irregular margins and little mycelium development (**Figure 8C**).

#### **3.5 Genetic improvement**

In México, 19 accessions of native chili pepper collected in the state of Morelos and 11 serrano chili accessions were selected considering its resistance to *Phytophthora capsici* that can be used in crop breeding [45, 46]. Twenty-six plant accessions were also identified in chili pepper with at least one individual showing resistance to *Fusarium* spp. and only two accessions from the gene bank resulted resistant to *P. capsici* and the mix including *Fusarium, Phythophtora* and *Rhizoctonia* [13]. Despite the germplasm selection for soil and seedborne fungal disease resistance no common bean and chile pepper cultivars for a specific response to soil fungi complex have been released in México.

#### **3.6 Crop rotation**

Crop rotation in the chili pepper production areas is influenced by farmer's tradition and the high economic income obtained with the fresh, dried and processed fruits, difficulting changes in the cropping systems. A similar response was observed for the common bean production under rainfed and irrigation monocropping systems. Then agronomic management recommendations need to be adjusted considering agroecological practices, including crop rotation, that contributes to improve the productivity and sustainability of local agroecosystems.

### **3.7 Agroecological practices**

In common bean, chili pepper, maize and most of the crops, agroecological practices and integrated management systems need to be implemented and systematized. Agroecological practices are poorly used in current agriculture in North-Central México, and some components need to be validated at the commercial level including biofertilizers, organic matter incorporation into the soil and the use of natural pesticides, as well as crop choice and crop rotation. Other options include intercropping, relay intercropping, agroforestry with timber, fruit or nut trees; allelopathic plants use (sunflower), direct seeding into living cover crops or mulch, reduced tillage, drip irrigation, biological pest control, and cultivar choice [47].

In Durango, marginal advances were achieved in organic fertilizer production and use, most of the products are not often available in sufficient quantity. Industrial production has been obtained only for compost in "La Laguna" region but high prices have been observed making it unaffordable for farmers. Lombri-compost, fulvic acid and other liquid biofertilizers were also produced at low amounts and short time period effects, variable composition, and ambiguous results have been reported. Some interesting results were obtained by using Biological Nitrogen Fixing bacteria (*Rhizobium* spp. and *Azotobacter* spp.) and mycorrhizic fungi, but their production and distribution need to be reinforced. High biomass producing species with appropriate carbon to nitrogen ratio (25) has been selected (*Pennisetum* sp.) to reduce costs for direct organic matter incorporation into soils [48], stabilize pH (6.5–7.0) and naturally release soil minerals for plant nutrition.

Studies on organic pesticides need to be strengthened obtain clear results and to generate recommendations for commercial plantings of common bean, chili pepper and other food and fodder crops. Crop choices have been explored in Durango, using canola (*Brassica* spp.), chickpea (*Cicer ariethinum*), amaranth (*Amaranthus* spp.), barley (*Hordeum vulgare*), sunflower (*Helianthus annuus*), sorghum (*Sorghum bicolor*), and Oats (*Avena sativa*). Some problems need to be solved to improve adoption programs for these crops, such as mechanization from sown to harvest, efficient production storage and commercialization process.

Agroforestry with timber (Scott's Pine: *Pinus greggii*) was implemented using governmental programs, but then abandoned due to prolonged technical periods (10 to 12 years), poor technical support, and food requirement by farmer's families. Studies corroborated that the common bean is better adapted in early years of Scott's pine plantations compared to forage crops (oats and maize) [49]. Increments in Wichita pecan tree (*Carya illinoensis*) plantation area have been observed in the last 5 years in Durango, due to high prices of the pecan nuts and commercial competence to apple production, although influence on local agriculture has not yet been determined. Sunflower is an allelopathic crop which has been used in Durango to reduce problems observed with perennial grasses, mainly bermuda grass (*Cynodon dactylon*). Although, difficulties has been also observed for seed supply and during the crop harvest and seed (achene) commercialization processes.

Direct seeding into living cover crops was probed without success due to pressure exerted by beef/dairy livestock production and the preferential use of crop residues and cover crops as fodder instead as a natural amendment, then low organic matter content is commonly registered in agricultural soils. Low organic matter combined with alkaline reaction in the soils reduces the availability of nutrients, presence of beneficial microorganisms, water infiltration and retention, and then aggravating drought, plant nutrient deficiencies and disease problems in several food and cash crops. Mulch and drip irrigation is used in some cash crops, even common beans, in reduced areas due to installation costs, expensive maintenance and impractical use with actual machines used along the growth period

*Importance of the Natural Incidence of the* Fusarium *Genus in Food Crops Established… DOI: http://dx.doi.org/10.5772/intechopen.100595*

(sowing, mechanical weeding, cutting and threshing process). Reduced tillage also has been implemented in small areas of Durango, but then abandoned due to specialized machinery requirements, increment in weed populations and excessive herbicide use; as well as long periods required before registering yield increments.

The use of the biological pests control has been implemented releasing natural predators of plague-insects causing production problems, but no clear results were observed. Cultivar choice is present in common bean including several landraces (Negro San Luis, Bayo Rata, Canario), improved cultivars (Pinto Saltillo, Pinto Centauro, PID 1 and NOD 1) and breeding lines (PT14053, NGO14013), although low genetic variation has been observed for resistance to *Fusarium* and other fungi included in the root-rot complex. However, differences have been observed for plant surviving or escape strategies avoiding severe problems caused by root and aerial plant diseases.

In chili peppers difficulties have been observed for cultivar change, due to traditional use of specific open-pollinated cultivars (landraces), high seed prices for commercial hybrids and specific traits observed in landraces for fresh and dried fruits, as well as for processed fruit (chile pasado) flavor. Similar traits were considered in other chili pepper cultivars (puya, güerito) used for specific preparations included in Durango's cousine (chile con queso and frijoles charros). However outstanding results have been observed by using tomato 'big plant', produced under nursery conditions [50], and technology could be used for producing pathogen-free chili seedlings.

## **4. Conclusions**

The *Fusarium* genus causes significant reductions in yield and seed or fruits quality in common bean, chili pepper and other crops sown in North-Central México. Low income for farmers and total crop losses are also observed in *Fusarium* infested plots affecting food availability and the local economy. Modern agricultural practices should be validated and implemented for sustainable production in common bean, chili and other important crops used in the Mexican highlands. Breeding for plant adaptation, disease resistance, water productivity and product quality are the main concepts in modern and sustainable agriculture.

Fusarium *- An Overview on the Genus*
