Effect of napier head smut disease on napier yields and the disease coping strategies in farming systems in central Kenya

S W Mwendia, M Wanyoike*, R G Wahome* and D M Mwangi

KenyaAgricultural Research Institute, Muguga South, Box 30148 Nairobi 00100
*University of Nairobi, College of Agriculture and Veterinary services, Department of Animal Production Box 29053, Kabete, Kenya
Mwendia2007@yahoo.com
 

Abstract

A survey was done in a total of 204 households in three districts of central Kenya, Kiambu, Thika and Nyeri to capture the dairy keeping systems, extent of napier head smut disease, coping strategies employed by the affected and the up take of a smut resistant napier accession (Kakamega I). The survey was designed such that at least 65 house holds were interviewed per district in three sub-locations. One of the three sub-locations was viewed as a "contact" sub-location in which a group of farmers had collected Kakamega I napier grass seed from the Agricultural Research Centre Muguga and the other two sub-locations were at 5km radius from the "contact" to capture the spread of Kakamega I and were regarded as "non-contact".

The results indicated that dairy cattle were mostly confined and all feed brought to them or zero-grazed in Kiambu and Thika districts while in Nyeri there was a combination of confinement and some grazing or semi zero grazing. Of all those interviewed 62.8 % of the households (HHs) had napier head smut disease. The estimated dry matter reduction due to smut ranged between 0.0002 - 0.265 t ha^-1 yr^-1. Of the 150 HHs that were randomly selected only 19% had the smut resistant Kakamega I. Coping strategies on napier head smut disease were mainly uprooting affected tillers and stools by the affected HHs.

Key words: contact, household, KakamegaI, non-contact, survey

Introduction

Napier grass was introduced in Kenya in purposely for mulching in coffee but farmers soon realised its high potential as feed for cattle (Boonman1993). Napier grass is the main fodder crop and is grown by over 70% of the smallholder dairy farmers (Bayer 1990; Stotz 1983; Staal et al 1998; Mwangi 1994) contributing at least 40% of the fodder availed to cattle in this system (McLeod et al 2001). The most critical constraint to this smallholder market-oriented dairy production is inadequate quantity and quality of feeds (Walshe et al 1991; Devendra 2001; Devendra and Sevilla 2002). Napier grass being vegetatively propagated, planting materials are easily spread among farmers. The appearance of napier head smut disease first reported in early 1990s has therefore raised serious concerns. It is reported to reduce napier grass herbage yield by 25 - 46 % (Farrell 1998). Efforts to manage the impact of the disease led to the identification of kakamega I as being resistant (Farrell 1998). Since then, there has been effort by Agricultural Research Centre - Muguga South to disseminate Kakamega I planting material to the affected farmers and 1383 farmers had collected its planting material by 2005. The specific objective of this survey was to solicit information from farmers on the effect of napier grass head smut on napier grass yields and their coping mechanisms.
 

Materials and methods

Study site selection

The survey was done using a structured questionnaire in three administrative districts of central Kenya, namely Nyeri, Thika and Kiambu. This was done with assistance of agricultural extension staff at the respective sub-locations who were selected after training. The Kiambu and Thika districts represented intensive and Nyeri the semi-intensive farming systems. The intensive system is characterized by land scarcity and cattle are kept in confinement while under the semi-intensive system there is relatively more land available and cattle are sometimes grazed. Three sub-locations were selected in each district. The first sub-location in each district was referred to as "contact" sub-location and constituted a group of farmers who had previously collected Kakamega I napier planting material from Agricultural Research Centre- Muguga. The other two sub-locations in each of the districts were referred to as "non- contact" sub-locations and consisted of farmers who had no previous direct contact with the research centre. The contact groups were Endarasha farmers co-operative in Endarasha sub-location in Nyeri District, Kiambaa farmers dairy cooperative in Kiambaa sub-location in Kiambu and Gakoe primary school parents teachers association (PTA) in Gakoe sub-location in Thika district. These sub-locations were mapped out together with all neighboring sub-locations at 5 km radius. Two sub-locations in each district were selected among those at 5km radius in reference to the contact sub-location one at lower and the other at a higher elevation. However, two more sub-locations were included in Nyeri as a result of the purposive sampling described below. The sub-locations selected and their descriptions are shown in Table1.

Households sampling

The sample size was 35 House holds (HHs) in each of the three contact sub-locations and 15 HHs in each of the non-contact sub-locations at the 5 Km radius in the three districts. Eighteen HHs of the 35 HHs in contact sub-locations were purposively selected from among farmers that had accepted kakamega I napier seed from the contact groups of the PTA and dairy cooperatives management. This was to ensure capture of information on the farmers who got Kakamega I material and how they shared with other farmers. This led to the inclusion of two more sub-locations (Charity and Mitero) in Nyeri to make up the 18 HHs purposively selected in the district. Households were selected randomly along various transects that were drawn by agricultural extension staff during training and transects followed roads. The first HH on the right at the start of the transect was interviewed, then 15 HHs were counted on the left and the 16^th interviewed, again 15 HHs were counted on the right and the 16^th interviewed. This sequence was maintained until the required sample size of HHs was interviewed.

Data collected

Quantitative data was collected on land size, herd size by cattle keeping system, napier grass acreage, proportions of napier stools affected by smut, HH estimate of biomass reduction due to napier smut and number of households with or without Kakamega I. Qualitative data included constraints to napier grass, headsmut coping strategies and fate of smutted napier grass.

Data analysis

Percentages were computed for constraints to napier grass production, headsmut coping strategies, fate of smutted napier grass, proportion of stools affected by smut by cattle production system, napier reduction ranges due to smut by cattle production system and districts by cattle production system in excel software while analysis of variance was done procedures of Genstat 5 (Lawes Agricultural Trust 1995) for herd size by cattle production system, cattle in lactation by cattle production system, napier: land size ratio by cattle production system and Tropical Livestock Unit by cattle production system. The factor was dairy production system and variables included herd size, number of lactating cows, napier land size ratio and Tropical Livestock Units.
 

Results and discussions

Cattle keeping systems in surveyed areas

From the onset, the study was planned to cover intensive system in Kiambu and Thika and semi-intensive in Nyeri. The field observations confirmed the cattle production systems. In Kiambu and Thika districts 93 and 94 % of the house holds kept their cattle under zero-grazing respectively while in Nyeri a total of 83% were kept under semi-zero grazing system (Table 2).

Herd size was lower in the stall-feeding system (P<0.01). The more intensive systems also had fewer lactating cows per household. Development of cattle production systems has been driven by increasing human population density, the subsequent reduction in per capita land holdings and thus the available grazing from extensive to more intensive systems of production (Bebe 2003; McIntire et al 1992). Bebe (2003) had noted that herd size in Kenyan highlands by smallholder farmers is no more than three cattle. As farmers intensify their systems, they keep smaller herds with lower proportion of heifers as this allows use of the scarce planted-fodder for cows, the most productive class (Bebe 2003). Although negligible in the only-grazing system, proportion of land under napier grass tended to increase from less intensive to the more intensive systems. McLeod et al (2001) reported that napier grass contributed at least 40% of the fodder availed to cattle in smallholder dairy systems in Kiambu central Kenya. Staal et al (2001) showed that in highly intensified systems in central Kenya the amount of land under napier grass in cattle keeping households was 0.15ha per TLU compared to 0.03 ha in less intensive system in the same area. In this study the more intensive areas had 0.31 ha of napier per TLU and only-grazing system had only a few stools. This implied an increase in napier grass use as fodder with intensification.

Perceptions of napiergrass production problems

Table 3 shows perceptions of napier grass production problems in all the surveyed households. According to respondents, about 63 % HHs perceived napier grass head smut as a constraint and this emerged as the most serious challenge to napier production.

The other disease mentioned was white mould by about 2.9% of respondents. As previously reported napier grass head smut affects about 25% of napier plots (Farrell 1998) and this seems to be on the increase. Napier grass pests comprising moles and termites were perceived as important by about 55% of the households. Lack of napier grass varieties was reported by about 8% of the HHs while adverse weather effects consisting of frost, cold and moisture stress was reported by about 13%. Category of others affected 2.9% of respondents and included napier theft, obnoxious weeds like couch grass and retarded growth.

Estimation of yield reduction due to napiergrass head smut, farmers' napier head smut disease coping strategies and napier grass delivery pathway

Napier is planted at a rate of about 10201 stools per ha at a recommended spacing of 1 x 1 m (Muyekho et al 1999). Its dry matter percent and dry matter yield are estimated at 16.3 % and 12 t ha^-1yr^-1 (Boonman 1993). On the basis of these, perceived reductions per stool and proportions of stools affected, production losses were calculated and these are reported in Table 4.

Napier head smut coping strategies are also reported in table 4. The estimated DM reductions were variable across the four production systems but the highest at about 0.27 tonnes DM/ha per year were experienced by farmers practicing stall feeding. This was a significant amount since for a milking cow of about 400kg with an estimated intake of 12 kg DM per day (ARC 1980; Mwendia 2000); this would feed it for about 22.5 days.

In intensive systems, fodder availability is a challenge even during the rainy season (Romney et al 1998) thus fodder reduction by smut disease is detrimental to the system.

The majority of respondents uprooted either the diseased stools or tillers while those planting the resistant variety were only about 10%. Some respondents planted afresh and applied manure hoping these would control the disease. Farrell (1998) found some farmers were uprooting diseased plants from their napier grass plots but did not indicate what they did with the diseased material. The disposal methods for the smutted napier grass used by majority of the respondents in the current study are ineffective. The material left on the land either on own farm or the roadside or used for mulching may be a source of future infections. Feeding the diseased material to cattle could be attributed to pressure due to inadequate fodder on farm (Romney et al 1998). However, spores ingested by the cattle are not known to be killed in the animal gastro intestinal tract and may be present in the feces which if used to manure susceptible napier grass plots will be a source of infection. Njuguna et al (2003) working with maize head smut found that fresh and dried cow dung from cows that had ingested Sporisorim reiliana which causes the disease still caused the disease when used to fertilize susceptible maize. It is only composted manure that did not cause the disease. However, it is doubtful that farmers allow the dung to decompose properly before use. Lekasi (2000) stated that farmers cannot tell when home-produced manure is ready for application. Of the disposal methods mentioned, only burning is likely to be effective and this was practiced by very few house holds in the study.

Planting of resistant variety was a strategy adopted by few respondents and of these a higher proportion was in the more intensive systems of production (Table 4). Among the randomly selected HHs, 13% of the HHs under the stall feeding system, 4.7% under the mainly cut and carry and some grazing, 1.3% under mainly grazing with some cut and carry and none under only grazing systems, had planted the resistant variety. The low adoption rate was due to a combination of several factors including lack of awareness and planting material. These results indicate a need to disseminate the technology and material to farmers in need.

The napier grass delivery pathways targeted in the survey were dairy co-operatives in both Nyeri and Kiambu districts and a primary school in Thika. The seed napier grass was delivered from KARI- Muguga South to the primary school that established a bulking site for distributing to primary recipients. Dairy cooperatives also received seed napier from KARI- Muguga South for distribution to primary recipients. Secondary recipients are those who received seed napier from primary recipients.

The number of secondary recipients of Kakamega I within location of primary recipient and in other locations was higher for stall feeding system. In fact the other systems never gave the material outside their locations (Table 4). The HHs in more intensive systems shared the material with at least 3 other HHs. In the three districts there was no household at or beyond the 5km radius sub-locations that had acquired the material directly or indirectly from the contact sub-locations. It was thus difficult to evaluate which pathway was better than the other. Perhaps this means that the napier grass distribution centres may have to be set up after every 5 km.
 

Conclusions

• The systems of dairy cattle production in the study areas are mainly stall feeding (zero-grazing), mainly cut and carry with some grazing, mainly grazing with some cut and carry and only grazing.
  
  
• The more intensive stall feeding and mainly cut and carry with some grazing production systems are threatened by napier grass head smut disease and stand to benefit more from dissemination of Kakamega I.
  
  
• The napier head smut coping mechanisms employed by the farmers are mainly uprooting diseased stools and tillers but disposal of the uprooted material posed a threat as potential sources of future infections.
  
  
• The more intensive systems planted more and shared napier grass planting material at a higher rate than the less intensive systems.
   

Recommendations

• Dairy farmers experiencing Napier head smut problem should use Kakamega I napier grass which is resistant to the disease and it would be better if farmers are able to share the its planting material with those who do not have.

• The uprooted disease material should neither be given to the cattle nor left on the farm as would still be source of infections.

• The material should be buried or burned.

• Farmers should also fertilize their Napier fields properly as stresses like infertile soils and lack of soil moisture seems to make the problem more pronounced.
   

Acknowledgement

Authors thank the directors of the collaborating institutions for enabling the work to be done. The assistance by the Ministry of Livestock and Fisheries officers in conducting the survey is highly is appreciated. We thank farmers who spared their valuable time to answer numerous questions without which this work would not have been possible. Thanks to the DFID through the Smallholder Dairy Project (SDP) for supporting the work financially
 

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