Striga: The Parasitic Weed and its Relation to Poverty, 03/'96




Striga: The parasitic weed and its relation to poverty

By Dr. Robert Shank, Agriculturalist, UNDP Emergencies Unit for Ethiopia

March 1996

Farmers choose terms that appropriately characterise their problems. In Amharic, Striga is called `Kitgyn' which literally means syphilis. The insinuation is that the land becomes unproductive and the condition becomes difficult to cure. In Oromiffa, Striga is called `Desso' which means `that which stunts another'.


The parasitic weed Striga, which attaches itself to the roots of plants and "sucks out" the nourishment, has caused extensive loss of cropland productivity in the drought-affected, food deficit areas of Northern Ethiopia. Estimated losses in infested fields of sorghum and finger millet range from 40-100%. Although mid- to highland infestations are currently light, infestations are likely to increase as soil fertility continues to decline. Infertile soil and drought have already caused serious infestations in the entire Western Zone (Humera to Shire) and the west edge of the Central Zone of Tigray. Striga is also serious in the sloping, shallow soils of the Abay, Tekeze, and Mereb watersheds where sorghum cropping is the most suitable choice for farmers.

Striga infestations flourish in conditions that also characterise the poorest farming communities (small plots, mono-cropping, lack of oxen and natural manure and lack of agricultural inputs) and, once areas are infested, Striga exacerbates the problems of overall poverty and food insecurity by decreasing yields.

Among the factors which influence both the inter relationship between poverty and Striga as well as the spread of Striga infestations are:

Sorghum, because of its high relatively high per hectare yield in poor soils, is the most suitable for the rural poor. However, all traditional sorghum varieties are susceptible to Striga infestations and, consequently, to the spread of Striga.

Sorghum's high yield in poor soils has also lead to sorghum mono-cropping as other, Striga immune, crops cannot offer the poor farmer the same potential yield. However, sorghum mono-cropping in Striga areas quickly increases the severity of Striga infestations and crop yields decline and food deficits mount.

Low and unreliable rainfall (400-600 mm) prevalent in many of the poor highland areas of the north means a high incidence of drought and crop failure, further contributing to food insecurity and poverty. However, Striga thrives on low rainfall or drought situations, can use up to 4 times more water than sorghum and its metabolic system stunts sorghum top growth which would shade and compete with the Striga.

Small land holdings and shortage of assets of the poor further limit the choice of crops and practices for controlling or rehabilitating land from Striga infestations. The small farmer must plant the majority of his land in sorghum to have any chance of providing enough food for the family. Late plowing due to the shortage of oxen subjects the crop to drought and the effects of Striga.

Inputs of chemical fertilizer and herbicides, which can help control or eliminate Striga infestations as well as raise yield levels, normally have low marginal returns in drought prone, Striga infested areas, making these farmers poor credit risks for input loans.

Poor soil fertility, especially soils low in nitrogen and organic matter, not only give poor crop yields but also contribute to increased Striga germination, increased flowering and seed production and prolonged Striga seed viability in the soil.

Although Striga infestation poses a major threat to many of the poorest farmers, the effects of Striga and the resulting loss in production throughout the community could be substantially reduced through several different techniques or combination of techniques:

increased emphasis on farmer education programmes and an integrated community commitment to restrict Striga seed production;

rehabilitation of Striga infested land through alternate crops or cropping techniques and cost effective interventions such as are currently used in on-farm demonstrations;

use of resistant sorghum varieties and other farming practices that increase productivity under soil moisture stress and eliminate Striga seed production; and,

innovative use of relief food resources during land recovery programmes - i.e. a food aid supported or conservation reserve "soil bank" type of programme - could also facilitate the elimination of Striga infestations.

As Striga often affects the poorest households, there is a direct relationship between infestation and poverty/food insecurity. This reports looks at the overall problem of Striga as well as the various control options that are currently being investigated.

Introduction and background

Striga hermonthica is a parasitic weed of grass cereals, specifically sorghum and finger millet in Ethiopia. Most commonly occurring on low nitrogen-fertility soils and under low rainfall ecologies throughout Amhara and Tigray Regions, as few as three plants per square meter can completely inhibit grain production. Attaching to the host root and transpiring at three times the normal rate, water and nutrients are shunted to the parasite. Striga also alters the hormone balance of the host, stimulating the crop to reduce shoot growth and extend root growth. Producing as high as 20,000 seeds per plant and remaining viable in the soil for up to 20 years, Striga infested soils loose their productivity and become characterised by masses of purple flowers.

The Agricultural Development and Crop Protection Department of the Ministry of Agriculture is responsible for giving advice to the regions in the area of weed pests and their control. In the late 80's, Drs. Chris Parker and Ann Stroud, FAO consultants on weed control, provided valuable assistance to Ethiopian scientists and extensionists. In 1994 the author published an information report[1] which was followed by an MoA allocation of a small fund for on-farm demonstrations of known Striga control measures. A total of thirty demonstrations were conducted in Welo, including the use of fertilizer, herbicide and hand pulling of Striga weeds. In 1994, another FAO consultant was provided for six days and a McKnight Grant application was suggested. Although the grant did not materialize, the number of demonstration plots allocated for 1995 was increased to 100, including all the zones in Tigray and Amhara Regions (see results below).

Demonstrated control measures utilized in the past two years have been effective and these experiences have more clearly defined MoA recommendations and confidence in controlling Striga. According to available information, Striga resistant sorghum varieties will be demonstrated in Striga affected areas and should be available to the farmers in limited supplies during 1997. The use of nitrogenous fertilizer is especially useful as, in addition to suppressing Striga germination and parasitism of the sorghum plant, it also results in an increased grain yield. Urea fertilizer also reduces Striga emergence and the need for weeding as well as the number of flowers and seeds produced on the Striga plant. Weeding of Striga and other broad-leaf weeds can be facilitated with 2,4-D herbicide but later emerging Striga must be weeded to the end of the season since Striga seed production on Sorghum roots can continue even after grain harvest. Hand-pulled Striga plants need to be disposed in a pit to prevent seed spreading. Grazing on infested fields can result in Striga spread since the seeds can remain viable after passage through the digestive tract of cattle.

Reducing Striga seeds in the soil and increasing soil fertility could be accomplished by crop rotation, especially with pulses, if adapted crop varieties were available; however, poor farmers will need supporting inputs to adopt practices which would increase unit land productivity. This would enable Striga infested areas to enter recovery programmes while assuring the farmer sufficient production from the remaining portion of his land to feed or buy food for his family.

Agro-economic relationship of Striga to poverty and the Striga survey in Welo

Striga appears to have co-evolved with the Ethio-Sudan sorghum and millet grasses, both wild and domesticated. The enzyme systems of the parasite thrive under low soil fertility and moisture stress, conditions often present in Northern Ethiopia. While most soils in Ethiopia have been depleted of fertility through removal of organic matter and limited use of manure, it is low fertility in combination with drought-induced stress and susceptible host cropping that predisposes the area to Striga. While many agriculturists point to reduced cattle numbers and availability of manure/organic matter as the cause of Striga infestation, it is likely that sorghum mono-cropping by the land-short farmer and the lack of options for rotation in this drought-prone area have led to build-up of Striga in Tigray and Amhara regions and not elsewhere in Ethiopia.

For instance, the MoA/Farm Africa project office in Axum (Central zone of Tigray) reports that farmers without oxen, especially women headed households, will get their land tilled and planted last and without manure fertilization, both conditions contributing to observed greater Striga infestation and drought induced poorer crop yields on these farms. Households with two oxen, in addition to the extra manure, are thought to earn extra cash from plowing, enabling the purchase of fuel. However rich or poor, manure is usually applied only to fields nearer the home; wealth and greater land holdings allow for pulse and teff rotational cropping of fields distant from the home, options that reduce Striga infestations but are not available to the land-short poor. Additional evidence that low soil fertility alone is not the cause comes from the three state farms in East Gojam zone (Amhara Region) where fertilized but mono-cropped sorghum yields had dropped to 10 quintals/hectare.

Conditions contributing to Striga infestation, spread and consequent land abandonment seem to be increasing. The Commission for Disaster Prevention and Preparedness (CDPP) reports Striga as a contributing factor to recent farmer migrations in North Gonder zone (Amhara Region). Moreover, Striga infestation seems to be the worst in the Western zone and the bordering areas of the Central zone of Tigray and may be moving east especially into drought-affected areas. Striga in the more humid/fertile areas of Maychew in South Tigray and Kombolcha in South Welo (Amhara Region) seems to be at the incipient stage as limited land holdings force increasing sorghum mono-cropping and soil depletion. Infestation is not uncommon as far south as Shewa-Robit, throughout the Abay, Tekeze and Mereb river valleys and the western escarpments of Gonder and Gojam (Amhara Region).

The International Institute of Tropical Agriculture in Nigeria has data that implies Striga spreads to new areas by contaminated grain seeds and the distribution of sorghum relief food is thought to be the means by which Striga has been accidentally introduced into three weredas in West Hararghe (Oromiya Region).

Dr. Stroud conducted a cause-effect relationship survey of 100 farmers whose sorghum crops were infested with Striga in six weredas of North and South Welo during the 1987 growing season. Approximately 93% of the farmers in the area had faced drought for five consecutive years. About 44% of these farmers had less than 1 hectare of land, 35% had only 1 ox and 17% owned no draft oxen even though they had lived in the area more than 25 years. Between 20-40% of the land was planted with teff but 40-70% was planted with sorghum because no other crop could replace its 7.5 quintal average productivity under the prevalent conditions of drought and low soil fertility. Most farmers utilized the long-season, Striga susceptible variety `Degalet', plowing at the beginning of the belg season in March, planting in late April, weeding until the end of the kiremt rains in September and harvesting in November-December.

Striga had been present in the area for over 20 years but was increasing in severity in some areas such as Kalu wereda. About 85% of the farmers reported severe damage to sorghum, 43% reported infestation on maize and 50% reported seeing Striga in their teff fields. (Striga on sorghum could have been growing on seedlings from the previous year crop.) Hand weeding, practiced by most farmers, was stopped too soon by virtually all farmers and should have continued even after the harvest to prevent seed production. Significantly, farmers with more severe infestations were found to weed fewer times and quit sooner. This is understandable because crop yields may have been so poor that it is justified to abandon the crop and seek cash labour elsewhere. Only 9% of the affected farmers reported placing the pulled Striga in a pit to prevent seed spreading while 85% reported throwing the weed out of the field, on the roadside, or the riverbank, which allows spreading to other areas. Crop rotation was seldom practiced because of the high starch-food requirement of the family and the climatic/market risk of planting cash crops or alternate food crops.

Major factors found to influence the Striga problem (from the Stroud Survey)

1. Rainfall timing and amounts

It has been observed throughout Striga areas of Asia and Africa that continuous wet periods are unfavourable to Striga development whereas wet periods with intermittent dry spells are very favourable. Thus farmers in Welo reported that Striga is `worse' in `good' belg rainfall years with wet and dry spells, probably due to favourable germination of sorghum seed and more shallow root development stimulating high numbers of Striga to germinate as well. In dry years the sorghum root systems tend to grow deeper where moisture is present and Striga seeds are less likely to germinate due to soil oxygen/carbon dioxide relationships. Since rainfall is erratic both in amount and timing, it is difficult to give the farmer any general recommendations on planting to avoid Striga favourable soil moisture relationships. Farmers think later planting is less affected by Striga but more affected by drought. Consequently they choose to plant as early as possible.

2. Soil conditions, type and fertility

In general it is drought stress/soil moisture, rather than soil type per se that influences Striga infestation. Clay soils are the most common soils in Northern Ethiopia and it is possible that Striga is worse on clay soils because their water holding capacity in the upper layer is greater, thus favouring high sorghum populations but shallow rooting. Other soils that store less water in the upper layers encouraging deeper crop rooting where the oxygen level is lower and less likely to favour Striga germination. These conclusions are also supported by the finding that farmers who cultivate twice (Shilshalo), as compared to once or not at all, have less Striga. If cultivation occurs early in moist soils, stirring the soil would bringing the roots into contact with additional Striga seeds and increase infestation. However, as may be the case in Welo, cultivation may dry the soil and destroy shallow, infected roots and therefore encourage deeper rooting.

3. Intercropping, rotation cropping and farming systems

The survey documented that farmers who intercrop have less Striga; however, as a whole, the report indicates that farmers saw no relationship. It may be that a number of factors may enter into the decision of whether an individual farmer intercrops. While the total yield is usually higher, the sorghum yields may be reduced, especially under drought conditions. Therefore, farmers who do intercrop tend to be the ones with enough land, oxen and labour to be interested in the higher value intercrop varieties.

The incidence of Striga has increased since Dr. Stroud's 1987 survey due to growing land pressures, decreasing land fertility and droughts. This increase in infestations has led to a renewed interest in investigations of new crops/varieties for rotations and different farming systems that would provide the resource-poor farmer with alternatives to sorghum mono-cropping.

4. Land tenure, marketing and input supply policies

Land tenure policies were found to influence Striga incidence. Insecure tenure and the hope for a reallocation of better land encouraged less Striga weed control, less careful husbandry practices and higher Striga incidence.

Fertilizer, especially nitrogen, which is essential to increase production and reduce Striga seed germination, flowering and seed production, must be made available especially to the land short farmer to enable him to alleviate the effects of mono-cropping and consequent Striga buildup.

Finally, Government stabilization of market prices would encourage intercropping/rotation cropping of higher value/lower yielding crops that reduce Striga seeds in the soil.

Research needs and problems

"Trapping" crops are those that induce `suicidal' germination of Striga seeds, i.e. trapping crop roots stimulate Striga seed germination as with sorghum roots, although in this case parasitism of the root is not successful. Trapping crops include sunflowers, flax, safflower, sunflower, cotton and most legumes. Adapted varieties of leguminous pulse crops such as soybeans, cowpeas, haricot beans, peanuts and pigeon pea seem promising for fixing nitrogen in addition to trapping Striga. Crops differ according to the number of Striga seeds trapped due to the extent of the root system and the amount of stimulant exuded from the root. To-date, however, the potential use of trap cropping for the control of Striga has not been promoted among farmers and more research is needed in alternative cropping practices for Striga control farming systems, including trap cropping, intercropping and rotational cropping. (Rotation with non-trapping crops like teff simply delays Striga germination until the next susceptible host crop. Soils in the Striga areas are often devoid of organic matter and micro-organismic decay of Striga seeds is thought to be minimal and has been recorded to take as long as 20 years. Farmers currently abandon Striga infested areas or leave them fallow but this is not as effective as rotation with trapping crops.)

The use of resistant sorghum varieties could be a key component in combating Striga since the lower level of stimulant exuded from the roots greatly reduces Striga germination. Three resistant varieties produced by the international research centers have been in the Ethiopian research system but were found to yield significantly less than the farmers' varieties due to their early maturity. It was decided, however, to release them this year because of the potential for their use in Striga affected areas, which are also short season and drought-affected. There is an immediate need for incorporating Striga resistance into the prevalent sorghum varieties used in Striga affected areas.

MoA fenced demonstration areas for showing farmers improved practices are frequently located in the most productive areas where little or no Striga exists. In fact it is difficult to find places for Striga control plots apart from the farmers field. While it is true that research and or demonstration plots should not be geared to poor husbandry practices, they must reflect the conditions faced by the majority of farmers, Striga certainly being one of the serious problems needing attention.

Extension and farmer education

In attempting to control Striga and its spread, the various factors leading to Striga infestation of cropland must be stressed repeatedly to both the farmers and the community as a whole as Striga can not be controlled or eliminated on just one or two plots. The whole farm community must be involved in Striga weed elimination and sanitation. The author thinks that drought may hasten Striga seed maturity and concludes that for effective control the entire farm community must undertake an area-wide control programme including weeding at flowering with repeat weedings until the end of the season and the sanitary disposal of Striga weeds in a burial pit.

Results from 1994 and 1995 on-farm demonstrations

Although the attrition rate of on-farm demonstrations was high in these drought agro-ecologies, completed on-farm demonstration showed promising results even in the first year. Utilizing the fact that nitrogen fertilizer inhibits Striga germination and attachment to sorghum roots, reduces Striga plant numbers and decreases hand weeding requirements, varying rates of Urea were applied. (Urea application rates had to be adjusted to the soil moisture due to the salt burning effect of Urea under dry conditions.) Even more effective in raising root-zone nitrogen would be `ring application' around individual plants rather than broadcast application which is commonly utilized. (In some cases it appears that the Striga seed load in the soil is so great that the crop growth resulting from the application of fertilizer seems to also produce more Striga plants. More research is needed to clarify whether this is caused by increased release of Striga stimulants by some very susceptible sorghum varieties.)

Until Striga flowering occurs, hand weeding is difficult because plants are not so easy to see and are brittle. Hand-pulling of one plant results in "tillering" and the re-growth of three or four new plants, thus discouraging the farmer even more. Also by flowering time, extensive physiological stunting and nutrient shunting have already severely reducing yield potentials. For this reason, 2,4-D herbicide was provided to the demonstration farmer for early and complete destruction of young Striga plants. Farmers were encouraged to weed successively at three week intervals thereafter until the end of the season in order to prevent Striga seed formation. Weeded Striga plants were disposed in a pit to prevent seed spreading.

The attached Table shows that recommended practices not only increased sorghum yields but also reduced Striga plant numbers. Changes in sorghum yields ranged from -1.23 to +20.83 quintal/hectare. On average the near 5 quintals increase in sorghum would have covered the cost of the 2 quintals of fertilizer and the litre of 2,4-D herbicide even in the first year of control. If applied in successive years, this practice would lead to reduce Striga numbers and eventually allow reduced fertilizer rates and costs. Attention this year to adjusting the nitrogen component of the fertilizer, adjusting fertilizer application rate to rainfall received, including legume intercrops and refining application of 2,4-D herbicide should further define input costs for controlling Striga and hopefully raise the economic feasibility of control.

Research and extension programmes for 1996

1. The Institute of Agricultural Research - Striga programme

To date, greenhouse pot screening of sorghum landraces for absence of the Striga stimulating root exudate has not identified any `indigenous resistant varieties'. Field trials, both at the Sirinka centre and the Mekele centre, have been hampered by the lack of Striga development on the station even under artificial infestation. Assistance from the African Highlands Project described below should facilitate research in infested areas starting this year. Reports of Striga reduction under intercropping from other countries was the impetus for Ethiopian trials which have identified soybeans and cowpeas as possible intercrop species in Striga areas.

2. The African highlands project of CIMMYT (International Wheat and Maize Improvement Centre) and ICRAF (International Centre for Agro-forestry Research) in co-operation with the Institute of Agriculture Research

Combining the use of leguminous shrubs with improved cereal cropping technologies has resulted in a new farming system called alley-cropping. The legume roots fix soil nitrogen while their leaves provide animal protein supplement and the branches can be used for fuel. Some species also produce a high protein edible seed crop.

The project aims to establish the suitability of this farming system to meet farmers needs, including those of the Striga infested areas through PRA (Participatory Rural Appraisal), greenhouse soil fertility-Striga control testing and on-farm demonstrations of applicable alley-cropping practices. Tests are being conducted for an initial two year period in Ethiopia, Kenya, Tanzania, Malawi and Rwanda. The on-farm Striga control work will be conducted in two weredas each in Western Tigray and North Welo zones.

3. MoA on-farm demonstrations and verification trials

The Ministry of Agriculture, in co-operation with Tigray and Amhara Regions, have recognized the seriousness of the Striga problem and have raised the priority of developing Striga control practices for their government mandated, on-farm demonstration programme. Three resistant varieties will be verified for their effectiveness in reducing Striga development, though their early maturity and short stature will limit their use to drought-affected, short growing season areas or to replanting following belg rainfall failure. Urea fertilizer application rates will be elevated with concurrent reduction in DAP usage to reduce Striga germination and infestation levels. Herbicide and weeding will again be utilized along with convincing the farmer to eliminate Striga seed formation. Where serious infestations occur and control difficult and discouraging, crop rotation will be encouraged.

In addition, a series of simple verification trials will be implemented to fine tune recommendations for future demonstrations. Farmers' own stock of `tolerant varieties' and other new varieties will be observed. The application rate of nitrogenous-based fertilizers and their interaction with the local, Striga susceptible, sorghum varieties will be tested. The cost and effectiveness of additional herbicides will also be observed. And, finally, alternative suitable crops such as trapping crops, intercrops and rotational crops, will be demonstrated.

4. Development Agent Striga control training programme in Tigray Region

The College of Dryland Agriculture and the Institute of Agriculture Research, with funding from GTZ, will give a two-day training on Striga control for 60 Development Agents from Western and Central Tigray zones.

5. Survey of Striga infestation in West Hararghe zone of Oromiya Region

The Crop Protection Division of the Oromia Agriculture Bureau will survey reported infestation in Habro, Boke and Daralabu weredas. The level of infestation will determine strategies aimed at containing the spread and reducing current infestation levels.

6. NGO assisted farmer Striga spraying programme

Recognizing the need for long-term control of Striga seed production and the shortage of sprayers available to the farmer, several NGOs will conduct trial programmes using small household trigger-type sprayers to apply 2,4-D herbicide. These sprayers, costing less than 50 birr, can be shared among several households and should utilize only a fraction of the herbicide normally required since the spray will be directed only at targeted Striga plants. Bi-weekly spraying by trained young adults could replace the current laborious hand weeding and thus encouraging households to be more persevering in long-term control.

Long-term prospects for controlling Striga and its implications for the government and donors

Striga can be spread within the farm community through a number of ways including:

-contaminated seed,

-contaminated soil through plows, animals feet, or eroding soil,

-passage through cattle grazing on Striga, and

-improper disposal of pulled Striga plants.

Although Striga was prevalent before the devastating droughts and land degradation of the last 10 to 20 years, infestations and the resulting loss in crop production have increased and will continue to do so until comprehensive control programmes are initiated. Many of the recommended control measures under consideration involve cash inputs. They are also less appropriate to the poor farmers who often have the highest levels of infestation rates and are least likely to undertake or continue the laborious job of hand pulling Striga weeds to the end of the season. Therefore, these factors should be considered in relationship to the community good and the common goal of stopping Striga seed production.

The cost of Striga controlling inputs may not be offset by higher crop yields, especially for the poor and in the short term. In drought prone Tigray Region, value/cost ratios (added crop value vs. cost input) for fertilizing sorghum are in the realm of 1.8 birr return for each birr spent. However these National Fertilizer Input Unit trials were not conducted in Striga areas.

As far as weeding to control seed production, mass mobilization for hand pulling Striga weeds could be considered an appropriate labour intensive intervention but is not likely to be sustained and could become an unfair burden on the poor. If herbicides are used to control Striga, returns may be nil initially but costs should decrease and returns from increased yields should increase over a five year period as Striga infestations come under control. Per area costs need not be exorbitant since 2,4-D costs as little as 40 birr per hectare for blanket coverage. Use of the hand-held, trigger type sprayer described above, would require only 1/10 or 4 birr/hectare to spray each plant of a 20,000 Striga plant/hectare infestation. Certainly this low cost should be added to the credit package of the farmer needing to control Striga.

The following are among the recommendations that could be considered by the appropriate or cooperating agencies:

Striga infested fields should be classified as to level of infestation and develop treatment plans according to cost/return potential. Sparsely infested fields could be farmed with a normal package of recommended practices. Treatment of moderately affected fields would require farmer and community commitments in labour for weeding combined with technical and credit assistance for the purchase of fertilizer and pesticides. Severely infested should be diverted to trap crop rotation for at least two years before returning to sorghum production. This may require giving land-short families other land during the interim, special credit arrangements for the poorest households, or using relief food resources to support land rehabilitation programmes.

There is a need to educate the community and develop commitment to a long-term (at least 5 year) plan. Particularly important in this regard is the need for farm community understanding that Striga infestations concern the whole community and control programmes must be undertaken must be undertaken collectively. Education and motivation to not allow even one Striga plant to produce seeds will be difficult, but critical in the control of Striga.

Striga control demonstration and training sites should be developed at wereda and Peasant Association levels and managed by local Ministry of Agriculture and Committee for Disaster Prevention and Preparedness. Since Striga infestation could be considered a food deficit-inducing condition, it should be possible to mobilize affected families to construct and demonstrate MoA Striga control procedures in typical enclosures, as well as on their own farms. To work toward these goals, the agriculture extension service of the MoA needs to be testing and demonstrating improved crops and cropping practices in Striga infested areas, in addition to the current more productive fenced trial sites. While it is good to show farmers the upper potential for crop performance, it is also necessary to portray typical farm conditions. Enclosed MoA trials currently are located on the most fertile, least drought affected land and certainly not continuously cropped with sorghum like most Striga infested farms.

All economically feasible control measures should be integrated with cost/return accounting for each component, i.e. economic input prioritizing. More reliable trapping crop rotations and intercrops need to be developed and their use encouraged. Striga resistant varieties adapted to the major agro-ecologies need to be developed by the fastest appropriate methods. The role of Striga infested sorghum seeds in the spread of Striga needs to be investigated. Sanitary disposal of Striga plant material needs to be insured.

It should be insured that all required inputs can be supplied to give sustained support to the farmer-participants efforts. Too often programmes receive start-up attention followed soon thereafter by cost-cutting and diversion of resources to other projects. Food deficient areas will continue to get aid as a result of failing to implement Striga control measures. Consideration should be given to using food aid as an incentive payment for rehabilitating productivity of the land and cutting the dependency cycle.

With the current government agriculture programme of training and assisting the farmer to increase productivity and food security, cost-effective inputs could be combined with farmer willingness to make concrete progress in eliminating Striga. The alternative of allowing Striga infestations to spread, or substituting with less productive crops, would only result in escalating food needs.

UN-EUE Tel.: (251) (1) 51-10-28/29

PO Box 5580, Fax: (251) (1) 51-12-92

Addis Ababa, Ethiopia

Table 1. Change in sorghum crop yields and Striga plant numbers as a result of recommended on-farm Striga control practices.

Location          Treatment*      Grain Yield       Striga          Hours/Weeding       
                                  Qt/Ha             Plants/Ha       Labour/Ha**         
Tigray               FP                    .14         55,000                           
AdiNebrid         (control)          .82   6.67     167                                 
T/Koraro          ISCP   FP         8.33   2.56     67                                  
AdiWalla          ISCP   FP         1.33   1.61     44                                  
AdiHagery         ISCP   FP         9.78   6.80     3,711                               
Sheraro           ISCP   FP         13.60   7.78                                        
MayTsemri         ISCP   FP            10.00                                            
East Gojam           FP   ISCP        5.20   7.80           689                         
E.Enawaga                                           44                                  
North Gonder         FP   ISCP        4.58   6.61                                       
Matema-1          FP   ISCP         4.09   5.22                                         
Matema-2          FP   ISCP         4.50   6.44                                         
South Welo            FP   ISCP        .34   1.78          511                   66.8   
Ambessel          FP   ISCP         12.80  17.11    133       444   30.6                
Ambessel   Kalu   FP   ISCP         6.50  10.00     844    1,078                        
Habru             FP   ISCP        -    -   9.67    644    2,722                        
Gubalaftu         FP   ISCP            30.50        967    6,311                        
Oromia  Bati          FP   ISCP      11.67  17.11     33,000            2775.0          
                                                    22,000          603.0               
AVERAGE             FP   ISCP        4.99   9.76                                        

* FP=farmers practice,(traditional cultural practices without inputs)

ISCP= Integrated Striga Control Package

** Hours X persons X days