Introduction

Haiti is a country of extreme poverty with a long history of environmental degradation, political instability and natural disasters (CIA, 2017). Out of approximately 10.6 million inhabitants (CIA, 2017), 56% are estimated to live on less than $2.41 per day, 25% live on less than $1.23 a day (World Bank, 2014) and 38.1% depend solely on small-scale farming for subsistence (CIA, 2017). Under nutrition is particularly widespread in Haitian children of whom 29.7% are classified as moderately malnourished and 18.9% as severely malnourished (UNICEF, 2016). In Haiti, one of the primary standards for treating acute malnutrition is with Ready-to-use Therapeutic Food (RUTF) (Iannotti et al., 2015; WHO, 2017).

Medika Mamba, Haitian Creole for "peanut butter medicine", is a peanut-based RUTF that has been produced and distributed in Haiti by the non-profit organization Meds and Food for Kids (MFK) since the early 2000s (MFK, 2017). MFK seeks to positively impact the Haitian economy by providing jobs at the RUTF factory located near Cap Haitien, Haiti, but also aims to provide further stimulus by sourcing 100% of their peanuts from local farmers. However, local purchasing is limited due to inflated market prices resulting from poor yields and low quality peanuts. As a result, MFK's strategy has been to improve the quality and quantity of peanuts produced in Haiti such that the market price would drop sufficiently for the factory to afford local purchase, and simultaneously increase grower profits by allowing significantly greater yields to be sold at a lower purchase price.

Therefore, in 2007 MFK linked up with U.S.-based University peanut specialists in order to obtain the technical expertise needed to improve local production. Since that time, research and extension efforts have been conducted in Haiti as part of a multi-disciplinary team consisting of MFK and other in-country partners and researchers at the University of Georgia and the University of Florida. This research has been funded by the Peanut and Mycotoxin Innovation Lab (PMIL) - part of the Feed the Future program, the US government's global hunger and food security initiative led by USAID (PMIL, 2017), whose overall objective is to improve livelihoods and health in developing countries through advances in peanut research in production, processing and markets.

Currently peanut is grown in Haiti primarily as a cash crop and is consumed by many as popular snack food (Nelson et al., 2003). Locally produced peanut butter is available in many small shops, and small packets of roasted peanuts are commonly sold by street vendors. As a minor crop, peanut is cultivated on approximately three percent of the total arable land in Haiti (FAOSTAT, 2016). Small-scale peanut production (<1 ha) occurs at the greatest frequency in the Northeast and the Central Plateau, but is also scattered widely across Haiti's diverse landscape. Planting, weeding, and harvest depends on manual labor, and production is generally organized by an elected community leader. The primary varieties grown in Haiti include two local landraces - one a runner market-type and the other a Valencia peanut market-type. Seed for planting is either saved by the grower or purchased on the market. The main production period occurs in the rainy season (typically late spring and early summer). An additional crop is planted in the late fall/early winter by growers in the Northern regions of Haiti where a second rainy season usually occurs during this period (G. Kostandini, personal communication).

Average pod yield in Haiti is exceptionally poor (870.9 kg/ha) (FAOSTAT, 2016) and aflatoxin contamination is common (Schwartzbord and Brown, 2015). There are a number of challenges to increasing peanut yield in Haiti including alkaline soils (Bargout and Raizada, 2013), low soil fertility (Nelson et al., 2003), poor seed quality (Nelson et al., 2003), inconsistent planting methods (our observation) and foliar diseases (Fulmer et al., 2014). Late leaf spot (Cercosporidium personatum) (Shokes and Culbreath, 1997) and peanut rust (Puccinia arachidis) (Subrahmanyam, 1997) are the two most destructive diseases of peanut in Haiti (Fulmer et al., 2014). These diseases are not typically managed in Haiti due to economic constraints and limited access to the appropriate resources. Furthermore, growers often mistake defoliation caused by foliar diseases with natural senescence. Management of leaf spot and rust in other developing countries consists of planting resistant cultivars, treatment with fungicide, crop rotation, destruction of plant residue and removing volunteer plants (Fulmer et al., 2016; Waliyar et al., 2000). Previous studies have documented the potential to significantly reduce foliar disease severity and increase yield in Haiti with resistant varieties developed by the International Crops Research Institute for the Semi-Arid-Tropics (ICRISAT) (Fulmer et al., 2012). However, negative roasting and quality issues did not favor wide-scale introduction resulting in the continued large-scale use of the local Haitian varieties.

One of the primary objectives of the PMIL project has been to identify a high yielding, disease resistant Valencia variety suitable for Haiti. Therefore, the purpose of this study was to evaluate the response of five advanced Valencia breeding lines compared to the local Haitian Valencia to foliar disease and yield performance and to determine whether there was an interaction with fungicide. A brief overview of this research has previously been published (Fulmer, 2018).

Materials and Methods

Results and Discussion

Late leaf spot and rust were both observed in these trials, but the latter was the most prevalent disease. The onset of both diseases (Fig. 1) was generally earliest in trials with the greatest amount of rainfall in the first 30 days after planting (Table 1). Final severity of both diseases differed between trials, and the highest disease pressure was observed in the first and third trial (Fig. 2). Although these trials were irrigated, overall disease severity (Fig. 2) was greatest in trials that had the greatest amount of rainfall (Table 1). However, there was no apparent association between the time of year the trial was conducted and final disease severity. It is therefore probable that differences in rainfall likely contribute more to the varying levels of foliar disease pressure than the time of year a trial is conducted in Haiti.

Fig. 1

Mean leaf spot incidence (A), peanut rust incidence (B) and yield (C) across varieties and fungicide treatments for three trials conducted at the Meds and Food for Kids (MFK) research facility near Cap Haitien, Haiti. Planting dates for each trial were as follows: MFK-2, 23 Mar. 2016; MFK-3, 24 Aug. 2016; MFK-4, 27 Jan. 2017. Error bars indicate the standard error of the mean (n = 4).

Table 1.

Rainfall for each trial conducted at the Meds and Food for Kids research facility near Cap Haitien, Haiti.

Fig. 2

Effect of variety on leaf spot (A, C, E, G and I) and peanut rust (B, D, F, H, and J) severity in five trials conducted in Haiti. A and B, first trial at Meds and Food for Kids (MFK) research facility near Cap Haitien, Haiti, C and D, second trial at MFK, E and F, third trial at MFK, G and H, fourth trial at MFK, I and J, fifth trial, conducted in the Central Plateau (CP) near Mirebalais, Haiti. Analyses were conducted separately for plots treated with and without fungicide and mean separations are indicated by upper and lower case letters, respectively. Bars with different letters are significantly different based upon Tukey's honestly significant difference test.

Disease severity was significantly affected by fungicide in almost every trial (Table 2). Variety had a significant effect on rust severity in every trial (Table 2). However, there was a significant variety × fungicide interaction in two of the trials for leaf spot and four of the trials for rust (Table 2). Based on the analysis of each simple effect with the SLICE option, it was clear that the main interaction was caused by the variety 309 Tan, which consistently had the lowest leaf spot and rust severity regardless of fungicide treatment (Fig. 2). All other varieties had a reduction in foliar disease severity with an application of fungicide (Fig. 2). Apart from 309 Tan, SGV0801 generally had lower levels of rust severity, but all other varieties were comparable to the local Haitian Valencia (Fig. 2).

Table 2.

P-values from the analysis of variance for all variables estimated for split-plot valencia/fungicide trials conducted from 2015 to 2017 in Haiti.

Final stand counts ranged from 69.6 to 97.4 percent plant emergence of total seeds planted and was significantly different in two of the five trials (data not shown). In the MFK-2 untreated plots, 309 Tan was significantly lower (73.2) compared to 309 Red (82.2), M2 (90.0), M3 (85.4), SGV0801 (83.3) and the local Haitian Valencia (83.0). In the MFK-4 plots treated with fungicide, the local Haitian Valencia (69.6) had significantly lower final plant stands compared to 309 Red (83.1), 309 Tan (76.1), M2 (85.2), M3 (87.8) and SGV0801 (88.1).

Yield varied by trial (Table 3) and differences did not appear to be associated with rainfall or final stand count. Differences in yield between trials were associated with differences in the seeding rate used for each trial. The lowest yielding trials, MFK-1 and CP-1, were planted at 3 seed/30.5 cm, but all other trials were planted at 6 seed/30.5 cm. Although not the primary objective of this study, these results corroborate other studies that have shown that higher planting densities tend to result in higher yields for bunch-type cultivars (Henning et al., 1982). Similar positive linear correlations between planting density and pod yield have been observed with the local Haitian Valencia (PMIL, unpublished data).

Table 3.

Effect of peanut variety and fungicide on pod yield in five trials conducted in Haiti.

Pod yield was significantly affected by fungicide in every trial, but variety was less consistent (Table 2); however, there was a significant variety × fungicide interaction in three of the trials (Table 2). Generally, there was not a statistical yield increase for any of the N.M. Valencia varieties compared to the local Haitian variety (Table 3). The variety 309 Tan consistently had the lowest numerical yields, but differences were not always significant (Table 3). The single exception was in the untreated plots in trial MFK-3, where rainfall and disease pressure was greatest (Table 1 and Table 3). Similarly, yield did not significantly increase in plots treated with fungicide except for trial MFK-3, but all other varieties (except SGV0801) had a significant yield increase in 3 to 4 of the five trials (Table 3). Fungicide did not have a significant effect in trial CP-5, likely due to the low disease pressure (Fig. 2). These results further validate that low-input fungicide regimes are extremely effective for reducing disease and increasing yield in Haiti. We have recently demonstrated that 3 to 4 fungicide applications can significantly improve pod yield for both runner and Valencia market-types by > 50 and 30%, respectively (Fulmer et al., 2016). Similar results of the efficacy of low-input fungicide programs have been reported in West Africa (Waliyar et al., 2000), Ghana (Naab et al., 2009) and Malawi (Subrahmanyam and Hildebrand, 1997).

The low yield results for 309 Tan were somewhat surprising because this variety has been reported to have excellent yield potential in Africa (N. Puppala, personal communication). It may be that disease pressure was not severe enough in Haiti to capture the full benefit of the high resistance levels in 309 Tan. Lower yields for 309 Tan may also be partially due to linkage drag which often occurs when breeding for resistance (Stalker et al., 2016).

Percent SMK was not significantly affected by fungicide (Table 2), but was significantly affected by variety in three trials (Table 2 and Table 4). 309 Tan was significantly lower than all the other varieties in the second trial, and numerically or statistically lowest in all other trials (Table 4). Overall, % SMK levels are comparable with other studies in Malawi (Subrahmanyam and Hildebrand, 1997), and were similar to % SMK values obtained in other trials conducted in Haiti (PMIL, unpublished data).

Table 4.

Effect of peanut variety on %SMK pooled across plots with and without fungicide.

Summary and Conclusions

The consistent yield response of susceptible varieties to fungicide applications observed in these studies emphasize the importance of managing foliar diseases in Haiti. However, as fungicide inputs are not widely used in Haiti due to practical and economic constraints, there is need to identify a high yielding, disease resistant varieties for smallholder farmers. In this study we demonstrated that 309 Tan has excellent resistance to late leaf spot and rust, but that this resistance did not result in a positive increase in yield and grade when compared to susceptible varieties. Similarly, while other varieties from the NMSU breeding program did provide higher yields compared to the local Haitian Valencia, the increase does not appear to be significant enough to justify the introduction of these varieties into Haiti at the present time. A major research objective in Haiti will be to develop a long-term strategy of incorporating improved traits of varieties like 309 Tan into the existing adapted varieties through plant breeding.

We would like to express our appreciation to the personnel at Meds and Food for Kids and Acceso Peanut Enterprise for providing research facilities and technical support. We also thank the following student interns from the Université Roi Henri Christophe and the Université Chrétienne du Nord d'Haiti for their valuable contributions to this research: Rodnie Valmy, Rodemane Saint Louis, Lainé Dorinvil, Frisnel Pierre and Jean-Baptiste Fontilus. Lastly, we thank the Peanut Mycotoxin Innovation Lab for funding this project.

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