2 Garlic bulbs that were used in the study

Garlic plant has been used as medicine for millennia because of its properties to inhibit microbial pathogen infections by its organo-sulfur compounds (Lawson, 1998; Ankri and Mirelman, 1999; Obagwu and Korsten, 2003). Its sharp odour, appetizer property and bitter taste make it to be used in food. It is also consumed fresh, as pills, capsules and extracts. Ayaz and Alpsoy (2007) reported that garlic is safe when taken in correct dosage as it can ulcerate the stomach when consumed in excess amounts. It kills bacteria, fungi, parasites and lowers glycemia and cholesterol levels in the blood. It has anti-tumor agents acting against cancerous cells.

Garlic has liver protector properties therefore known to protect the human body against many illnesses. A. sativum contains a compound known as allicin which is effective against a wide range of bacterial and fungal species (Stoll, 1998). Cavallito et al. (1944) reported that the anti-bacterial principle of garlic is diallyl-thio-sulphinate compound known as allicin. Reports by Stoll and Seebeck (1951) showed that allicin is produced during the crushing of garlic cloves by the interaction between the amino acid alliin and

the enzyme alliinase. Allicin is a precursor of a number of secondary products formed in crushed garlic and possesses various biological activities.

Cellini et al. (1996) and Lernar et al. (2000) reported that garlic has an anti-bacterial agent, being effective against many gram negative and positive bacteria like Helicobacter pylori, E. coli, Lactobacillus casei and this effect is sourced from allicin in it. Components like bio-flavonoids and sulphur have value in preventing infections. Active substances of garlic such as allistatin I and allistatin II are powerful against

Staphylococcus and E. coli (Baytop, 1999; Ayaz and Alpsoy, 2007). Imai et al. (1994), Ayaz and Alpsoy, (2007) pointed out that garlic water had been used in typhoid and meningitis treatment. Fumes from garlic have been used in treating whooping cough. Garlic wicks are used to treat yeast infections and garlic soup used to treat pneumonia. It also controls Candida albicans, Histoplasmacapsulatum, Aspergillus, Trichophytum and

Penicillium species (Imai et al., 1994).

It has been demonstrated that garlic extracts can be used in the prevention of gastritis and stomach cancer which are caused by H. pylori (Limurca et al., 2002). Chopped garlic added to raw meatball, which is a traditional food product in Turkey had a slowing-down effect on microbial growth in ground meat depending on garlic concentration (Aydin et al., 2007). Josling (2001), Hanafy et al. (1994), and Weber et al. (1992) demonstrated that garlic was effective both against influenza B and herpes simplex viruses. It was also used successfully against pertinacious virus in horses. They also reported that garlic

mobilizes immune system and empowers the defence ability of the body against infectious organisms.

Garlic has been used against Candida spp., Aspergillus spp. and Cryptococci as an effective anti-fungal substance (Ayaz and Alpsoy, 2007). It was also observed that a combination of Amphotericin B which is an anti-fungal treatment for mycoses, with allicin was a promising strategy for the therapy of candidiasis (Ogita et al., 2009). Ledezme et al. (1996) carried out a clinical and mycological study made on Tinea pedis

showed that an organo-sulphur component from garlic, a 0.4% cream form was used for seven days. Caporaso et al. (1983) reported that anti-fungal activity in fresh garlic taken orally, the antibody forming against Candida and Cryptococcus species are limited.

According to Kurucheve and Padmavathi (1997), garlic extract was used on seeds to depress the growth of Pythium aphanidermatum by inhibiting hydrolytic enzymes production by the pathogen. Reports by Upadhyaya and Gupta (1990) showed that ethanol extracts of garlic had inhibitory effect against Curvularia lunata. According to Tansey and Appleton (1975), garlic extracts have shown inhibitory effect on the growth of a number of fungi. Shalaby and Atia (1996), reported garlic to be effective against

Fusarium solani, Rhizoctonia solani, and Sclerotinia sclerotium that causes damping off in water melon and cantaloupe. According to Portz et al. (2008), allicin component in garlic is active against a wide range of pathogens both in vitro and in vivo. Curtis et al. (2004), reported that garlic is effective against Phytophthora infestans on tomato seedlings. Reports by Bowers and Locke (2000), and Bianchi et al. (1997), showed that

garlic extracts inhibit mycelial growth of F. solani and R. solani. According to Qvarnstrom (1992) only 2-10 % of the leaf areas were infected by Erysiphe cichoracearum in cucumber plants that were treated with 5 % garlic extract compared to 83-85 % in the control treatment. According to Singh et al. (1995), active compound of garlic extracts had complete inhibition on conidial germination of E. pisi when applied at the rate of 25mg/liter and when applied at 100mg/liter the extracts controlled powdery mildew in growth chamber.

Research by Locke (2006) showed that red garlic contained flavonoids and saponins that exhibited anti-bacterial properties against Bacillus subtilis. Ayazpour et al. (2010) revealed that high concentrations of A. sativum leaf extracts increased mortality of

Tylenchulus semipenetrans in laboratory conditions. Fadzirayi et al. (2010) reported that garlic extract has indirect effect on nematode populations as it disrupts their mobility, food absorption and reproduction. According to Block (2010), garlic oil offers significant protection to crops against free-living soil inhabiting nematodes.

2.2.2 Ginger

Zingiber officinale plant is classified under the family Zingiberaceae. It is a creeping perennial plant with a slender stem. Ginger does well in hot and moist climate with some shading and loam soils that are well tilled to allow rhizome expansion (Herbs, 2000). It is usually planted in rows at spacing of 60 cm between the rows and 30 cm between the plants. It has an underground stem (branched rhizome) which is thickened to form structure like a swollen hand (Abdel-Azz et al., 2006). The outer skin is brown and is

usually removed before use (Plate 2.3). The inner part is yellow in color. Shoots (pseudostems) arise from buds on the rhizome. The rhizome is consumed as a delicacy, medicine or spice. It is used extensively for domestic and commercial purposes.