Major Weeds of Ecuador. III. Plantains 1

Plantain ( AAB) is a tropical fruit cultivated in Canton El Carmen, Ecuador in 41650ha. Local population of Ecuadorian Coast and Eastern part of the country consume its fruit cooked or also raw when it is ripe. One of the constraints to its production is weed incidence, which reduces crop yields and compels farmers to spend on weeding practices throughout the year. Knowledge of weed species with the highest frequency/abundance and the factors that determine their presence in the crop as a way to better design weed management strategy. A weed survey was carried out in in 135ha of plantains during the period of September 2014 and May 2015. Half of the fields checked during winter or rainy period (December-May), while the rest during summer or dry season (June to November). Selected fields were plantations of var. Barraganete mainly planted in rows spaced 3m and 1 or 1,5m between plants on of medium-textured soils, aerated, with good water retention and medium fertility. Fertilization of the plantations was with NPK formula 10-30-10 at unknown rates. Weed cover was visually assessed using a scale 0-5, where 1- up to 5% weed cover and 4-more than 50%. These values were processed to determine Absolute and Relative Frequencies, average weed cover and finally Severity Infestation (SI). Field evaluations resulted in grand total 44 weed species belonging to 22 families. Overall weed cover was an average of 2,5 during rainy period, where perennial Geophila macropoda (Ruiz & Pav.) DC. is the prevailing species. Total weed cover was 0,35 during dry period, where the prevailing species were grasses R. cochinchinensis and Panicum trichoides Sw., and several dicots. Weed flora changes according to herbicide use in both seasons, but G. macropoda is again the prevailing species in paraquat-treated fields during the rainy season and in glyphosate-treated and hand-weeded areas during dry season. The result suggests the convenience to evaluate G. macropoda as possible cover to smother weeds in plantains of El Carmen combined with other control measures.

Plantain (Musa paradisíaca or Musa AAB) is a tropical fruit cultivated in Canton El Carmen, Ecuador in 41650ha. Local population of Ecuadorian Coast and Eastern part of the country consume its fruit cooked or also raw when it is ripe. One of the constraints to its production is weed incidence, which reduces crop yields and compels farmers to spend on weeding practices throughout the year. Knowledge of weed species with the highest frequency/abundance and the factors that determine their presence in the crop as a way to better design weed management strategy. A weed survey was carried out in in 135ha of plantains during the period of September 2014 and May 2015. Half of the fields checked during winter or rainy period (December-May), while the rest during summer or dry season (June to November). Selected fields were plantations of var. Barraganete mainly planted in rows spaced 3m and 1 or 1,5m between plants on of medium-textured soils, aerated, with good water retention and medium fertility. Fertilization of the plantations was with NPK formula 10-30-10 at unknown rates. Weed cover was visually assessed using a scale 0-5, where 1-up to 5% weed cover and 4-more than 50%. These values were processed to determine Absolute and Relative Frequencies, average weed cover and finally Severity Infestation (SI). Field evaluations resulted in grand total 44 weed species belonging to 22 families. Overall weed cover was an average of 2,5 during rainy period, where perennial Geophila macropoda (Ruiz & Pav.) DC. is the prevailing species. Total weed cover was 0,35 during dry period, where the prevailing species were grasses R. cochinchinensis and Panicum trichoides Sw., and several dicots. Weed flora changes according to herbicide use in both seasons, but G. macropoda is again the prevailing species in paraquat-treated fields during the rainy season and in glyphosate-treated and hand-weeded areas during dry season. The result suggests the convenience to evaluate G. macropoda as possible cover to smother weeds in plantains of El Carmen combined with other control measures.

MCDA.000707. 9(2).2021
One of the major constraints to the plantain production is weed incidence, which affects the crop shortly after its planting, and may reduce yields in already established plantations. In El Carmen hand-weeding is the most common control method, but some farmers also use foliar-applied herbicides, but without any particular system and/or schedule.
The best way to control weeds is through previous knowledge of those species with the highest frequency/abundance and the factors that determine their presence in the crop during the two seasons of the year (dry and rainy) in the coastal zone of Ecuador. This information helps to integrated control measures with an adequate expenditure of the farmer's available resources. The present study conducted throughout the 2014 dry period and the 2015 rainy period in plantain of El Carmen focused this purpose.

Material and Methods
A weed survey was carried out in 135 ha of plantains during the period of September 2014 and May 2015. Half of the fields checked during winter or rainy period (December-May), while the rest during summer or dry season (June to November). Selected fields were plantations of var. Barraganete mainly planted in rows spaced 3 m and 1 or 1,5m between plants on of medium-textured soils, aerated, with good water retention and medium fertility. Fertilization of the plantations was with NPK formula 10-30-10 at unknown rates.
Visual evaluation of weed cover was conducted using the same scoring system (see below) and data processing reported previously [3]. This time field route was going in two diagonal crossing directions of each field. Evaluation consisted of the cover of each species present and the total weed cover. Sites chosen for evaluation were 8-12 depending on the total area of each field.

Scale-cover
Data processed to determine Absolute Frequency (FA), i.e. the number of times each species was found in each site, and Relative Frequency (F) in %: F=FA/no. sites in each field infested by a species x 100 Then with ΣI-Sum of the cover values and its average IM: Where N is the number of fields infested by any species Finally, Severity Infestation (SI) as:

Result and Discussion
Field evaluations resulted in grand total 44 species belonging to 22 families. Prevailing species were dicots of C 3 photosynthesis, but a few grasses were present in spots with lack of plantain leaf shade (Figures 1 & 2).

MCDA.000707. 9(2).2021
Total weed cover was only 0,35 during dry period. The weed stand and composition differ from the ones recorded during rainy season (Figure 4), where two grasses appear among the prevailing plants, such as R. cochinchinensis and Panicum trichoides Sw., as well as dicots Conyza bonariensis (L.) Cronquist, G. macropoda, L. aestuans, annual climbing Momordica charanthia L., and common bracken. Other plants as E. hirta, E. heterophylla, Phyllanthus niruri L. and E. sonchifolia show medium SI values. One can expect to have the same weed stand during the dry season. However, A. flavescens, not recorded during rainy period, shows the highest SI value in paraquat-treated fields (Figure 6), while G. macropoda did the same with the application of glyphosate or hand weeding in the fields. B. pilosa and E. heterophylla were more abundant in hand-weeded fields. R. cochinchinensis and A. gangetica show medium SI values in fields treated with either paraquat or glyphosate. R. cochinchinensis stand should not be underrated; it is a C4 photosynthesis plant susceptible to shade, so its presence is an indicator of infested spots by low dense plantain leaf canopy probably due to intense sigatoka disease infection. The stand of C. bonariensis in fields treated with glyphosate is not new. Several authors [4][5][6][7] have reported glyphosate-resistant biotypes of this plant and other species of the same genus, but it is difficult to assert the existence of such biotypes due to the lack of systematic herbicide application in El Carmen. Repeated glyphosate use brings about problems of resistance. Therefore, a relevant test of resistance is pertinent. The lack of schedule for the use of the already-mentioned herbicides makes difficult to determine a pattern of the weed composition in plantains. Fields have shown a variable weed cover in both seasons. Although weed abundance was much lower during rainy season, none of the fields show outstanding weed control.

Copyright © Ricardo Labrada
MCDA.000707. 9(2).2021 The root system of Musaceae plants is shallow, hence any weeding practice should avoid harm it [8]. Annually four handweeding operations are required in established plantains or bananas fields to obtain high yields [9]. This situation changes when it is a weed control in a new plantation, where weeding is carried out within 7-9 months after planting [10].
The solutions to the problem of weeds has been the use of herbicides, initially with foliar-applied paraquat, later with systemic glyphosate. Herbicides became a suitable alternative to reduce weed stand and save farmers' labor, but at present, there are concerns about the human safety of both compounds. Breathing in paraquat may cause lung damage and can lead to a disease called paraquat lung [3]. It also causes damage to the body when it touches the lining of the mouth, stomach, or intestines. In the case of glyphosate, its repeated application during the last three decades also causes serious health consequences in food, water and air [2].
Therefore, the most convenient option for weed control is the use of cover crops, which is recommended by various authors for bananas and plantains plantations [6,8,12]. The main finding in this study has been the predominance of G. macropoda in different areas even in herbicide-treated fields. Cover of this plant reduces erosion in all soil types in banana plantations of Limón in Costa Rica and is useful for weed smothering; it also reduces the reliance on herbicides for weed control [13]. In Ecuador G. macropoda seems to be useful as cover in cocoa plantations since the plant is rich in macro elements (NPK) and stimulates bacteria population growth in soil [5]. However, more research is required to determine the usefulness of this plant as cover for suppressing weeds [14][15][16][17][18]. In plantain areas of Rocafuerte in Ecuador other than El Carmen, some stand of G. macropoda treated with paraquat showed scorched and chlorotic leaves, a sign of tolerance to this herbicide. G. macropoda may well prevent part of weed infestation possibly complemented with other weeding operations.
A major emphasis on weed management in plantains of El Carmen may bring about increased crop yields and net return of the produce.

Conclusion
Results clearly indicate the need to study and validate Geophila macropoda cover for smothering weeds. Such a cover may also stimulate growth of bacterial population in soil as to prevent problems of erosion.
Studies of the use of alternative foliar and soil-acting herbicides in plantains of El Carmen should be carried out with a risk assessment of possible environmental problems and likely effects on human being.