*2.4.1* Cucumber mosaic virus *(CMV)*

*Cucumber mosaic virus* (CMV) is an important viral disease of pepper with a worldwide distribution. In Africa, the virus has been reported in Uganda, Zambia,

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pathogens.

*Management of Viruses and Viral Diseases of Pepper (*Capsicum *spp.) in Africa*

Tanzania, Ethiopia, Zimbabwe, Kenya, Malawi, Madagascar, Sudan, Rwanda, Ghana and Nigeria [14, 45]. Although the virus exists as a number of strains, all are apparently capable of infecting pepper and differ only in their symptom expression. The age of a plant at the time of infection strongly influences what type of symptoms will be manifested. Symptoms of naturally affected pepper plants vary and most prominent ones are mild mosaic and dull-coloured leaves, mottling, shoe string, fern leaf, vein banding, vein clearing, leaf deformation, stunted growth and reduced fruit size [46, 47]. More than 80 species of aphids transmit the virus in a non-persistent way but *Aphis gossypii* and *Myzus persicae* are the most efficient [48]. Additionally, transmission can be through seeds, parasitic weeds and mechanically

Strategies to delay early infection can be used to enhance yield. Isolation of pepper from weedy border areas or growing them next to taller border plants such as maize, which can function as a non-susceptible host, use of certified seeds and plants, screening and disinfection of infected mother stock, washing and disinfecting of hands and tools, and planting of resistant pepper genotypes constitute the

The genus *Alfamovirus* consists of ssRNA viral particles. A typical member of this genus is *Alfalfa mosaic virus* (AMV) having natural host range including over

*Alfalfa mosaic virus* (AMV) is distributed worldwide, having a wide host range. In Africa, it has been reported in Zambia [50]. The virus is transmitted mechanically and in a non-persistent manner by numerous aphid species. Transmission of AMV also occurs through pepper seeds or pollen [9]. Typical symptoms associated with AMV in pepper include bright yellow or blotchy white mosaic patterns on pepper leaves [6]. Additional symptoms include stunted growth with deformed and blotchy fruits, especially if plants are infected at young stage. *Alfalfa mosaic virus* can cause important yield losses and increased susceptibility of pepper to other

*Alfalfa mosaic virus* can be successfully managed by reducing aphid population by use of insecticides. The use of resistant varieties and regular rouging of weeds

The genus *Tospovirus* consists of important species of plant viruses that cause great losses in many economically important crops. Members of this genus have tripartite ssRNA particles about 80–120 nm in size [42, 52]. The major virus species in the genus *Tospovirus* is *Tomato spotted wilt virus* (TSWV), which infects various

from the fields are effective means to manage the virus [51].

*DOI: http://dx.doi.org/10.5772/intechopen.92266*

[26, 49].

*2.4.1.1 Management of CMV*

**2.5 Genus:** *Alfamovirus*

effective means of managing CMV [47].

*2.5.1* Alfalfa mosaic virus *(AMV)*

*2.5.1.1 Management of AMV*

**2.6 Genus:** *Tospovirus*

*Capsicum* spp. in Africa [13].

250 plant species and is closely related to CMV [13].

*Management of Viruses and Viral Diseases of Pepper (*Capsicum *spp.) in Africa DOI: http://dx.doi.org/10.5772/intechopen.92266*

Tanzania, Ethiopia, Zimbabwe, Kenya, Malawi, Madagascar, Sudan, Rwanda, Ghana and Nigeria [14, 45]. Although the virus exists as a number of strains, all are apparently capable of infecting pepper and differ only in their symptom expression. The age of a plant at the time of infection strongly influences what type of symptoms will be manifested. Symptoms of naturally affected pepper plants vary and most prominent ones are mild mosaic and dull-coloured leaves, mottling, shoe string, fern leaf, vein banding, vein clearing, leaf deformation, stunted growth and reduced fruit size [46, 47]. More than 80 species of aphids transmit the virus in a non-persistent way but *Aphis gossypii* and *Myzus persicae* are the most efficient [48]. Additionally, transmission can be through seeds, parasitic weeds and mechanically [26, 49].

#### *2.4.1.1 Management of CMV*

Capsicum

exclusively transmitted by the whitefly (*Bemisia tabaci*) in a persistent and circulative manner. These virus species have circular single-stranded DNA (ssDNAs) particles approximately 30 nm in length and 18 nm in diameter. Examples of important

*Pepper leaf curl virus* (PepLCV) has been found in different countries of Africa and is responsible for several epidemics causing severe economic losses. Transmission of PepLCV is most damaging when plants are infected at early growth stage preventing the proper formation of flowers resulting in low fruit production. Symptoms of PepLCV include severe stunting, flower bud abscission, reduced pollen production, upward curling of leaves, leaf chlorosis and elimination of fruit

The most widely used treatments include use of insecticides and other cultural

methods to control vector population. Other methods to control the spread of PepLCV include planting resistant or tolerant plants, crop rotation and border

*Tomato yellow leaf curl virus* (TYLCV) is *one* of the most destructive viruses affecting a wide host range of vegetable crops, including Okra (*Abelmoschus esculentus*), tomato (*Solanum lycopersicum*), sweet and chilli pepper (*Capsicum* spp.), tobacco (*Nicotiana tabacum*), common bean (*Phaseolus vulgaris*) and some weeds [41]. The virus has been reported in *C. annuum* in Tunisia [42]. However, its distribution spreads across East, West and Central Africa. Movement of infected plants or virus-carrying whiteflies aids the spread of the virus. Typical symptoms of TYLCV in infected pepper plants include interveinal yellowing, leaf curling and

Plastic mulching has been effective in the control of whitefly populations in pepper fields. Other strategies for managing TYLCV include raising of seedlings in pest-proof nurseries, adoption of crop rotation, use of insecticides, selection of resistant varieties for planting, improved cultural practices to remove weeds and

The genus *Cucumovirus* comprises tripartite ssRNAs encapsidated in small icosahedral particles approximately 29 nm in diameter. Viruses in this genus infect

*Cucumber mosaic virus* (CMV) is an important viral disease of pepper with a worldwide distribution. In Africa, the virus has been reported in Uganda, Zambia,

over 1200 plant species worldwide [44], including weeds and wild species.

begomoviruses affecting pepper include PepLCV and TYLCV.

production. Yield losses may be between 90 and 100% [39].

*2.3.1* Pepper leaf curl virus *(PepLCV)*

*2.3.1.1 Management of PepLCV*

planting, and plastic mulching [40].

*2.3.2* Tomato yellow leaf curl virus *(TYLCV)*

stunting which cause critical production losses.

*2.3.2.1 Management of TYLCV*

alternative host plants [43].

*2.4.1* Cucumber mosaic virus *(CMV)*

**2.4 Genus:** *Cucumovirus*

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Strategies to delay early infection can be used to enhance yield. Isolation of pepper from weedy border areas or growing them next to taller border plants such as maize, which can function as a non-susceptible host, use of certified seeds and plants, screening and disinfection of infected mother stock, washing and disinfecting of hands and tools, and planting of resistant pepper genotypes constitute the effective means of managing CMV [47].

#### **2.5 Genus:** *Alfamovirus*

The genus *Alfamovirus* consists of ssRNA viral particles. A typical member of this genus is *Alfalfa mosaic virus* (AMV) having natural host range including over 250 plant species and is closely related to CMV [13].

#### *2.5.1* Alfalfa mosaic virus *(AMV)*

*Alfalfa mosaic virus* (AMV) is distributed worldwide, having a wide host range. In Africa, it has been reported in Zambia [50]. The virus is transmitted mechanically and in a non-persistent manner by numerous aphid species. Transmission of AMV also occurs through pepper seeds or pollen [9]. Typical symptoms associated with AMV in pepper include bright yellow or blotchy white mosaic patterns on pepper leaves [6]. Additional symptoms include stunted growth with deformed and blotchy fruits, especially if plants are infected at young stage. *Alfalfa mosaic virus* can cause important yield losses and increased susceptibility of pepper to other pathogens.

#### *2.5.1.1 Management of AMV*

*Alfalfa mosaic virus* can be successfully managed by reducing aphid population by use of insecticides. The use of resistant varieties and regular rouging of weeds from the fields are effective means to manage the virus [51].

#### **2.6 Genus:** *Tospovirus*

The genus *Tospovirus* consists of important species of plant viruses that cause great losses in many economically important crops. Members of this genus have tripartite ssRNA particles about 80–120 nm in size [42, 52]. The major virus species in the genus *Tospovirus* is *Tomato spotted wilt virus* (TSWV), which infects various *Capsicum* spp. in Africa [13].
