**1.5** *Hibiscus* **(***H. rosa-sinensis* **L.)**

A number of fungal diseases commonly infect hibiscus plants; in addition, physiological disorders also occur [18]. Leaf spots caused by several species of fungi cause brown or black circular or irregular shaped spots on the leaves [18]. Sooty mold is a black fungus on the upper surfaces of leaves, growing in the secretion of aphids, mealybugs, many scales, and immature whiteflies. The mold spoils the appearance of foliage but is not particularly injurious to the plant [18]. Root rots and collar rots, one of several species of fungi causing soft rotting of roots and sometimes also stems. Infected plants often wilt as though they are short of water [18]. Anthracnose by *Colletotrichum gloeosporioides* (*Glomerella cingulata*) [19]; powdery mildew by *Podosphaera* sp. [20]; dieback disease by *Botrytis* sp. and *Erwinia* sp.; wilt disease by *Fusarium oxysporum* and *Verticillium*; Choanephora blight caused by *Choanephora infundibulifera* [21]; botrytis blight by *Botrytis cinerea* [22]**;** hibiscus witches broom disease caused by *Candidatus* Phytoplasma brasiliense [23]; Phytophthora disease by *Plagithmysus nicotianae* var. *nicotianae* [24] and rust by *Kuehneola malvicola* were also reported [25].

Incidence of Leaf blight disease by *Nigrospora sphaerica* was observed in December (**Figure 5**) and anthracnose disease by the pathogen *C. gloeosporioides* was observed from August that gradually declined in the month of December on *H. rosa-sinensis* in Bangalore. Anthracnose disease exhibited the highest disease index of 29.4% in October and the extent of infection ranged from 2 to 4% (**Figure 6**).

#### **1.6 Noni (***M. citrifolia* **L.)**

This plant is known to be susceptible for some fungal diseases. Anthracnose caused by *C. gloeosporioides*, by which small brown-shaped spots of varying size (0.5–2.5 cm) appear on the leaves that gradually enlarge and coalesce. The center of the coalesced lesion turns grayish white leaving a shot hole symptom. Under humid conditions,

*Diseases of Medicinal Plants Cultivated in Karnataka and Their Management DOI: http://dx.doi.org/10.5772/intechopen.104632*

**Figure 5.** *Leaf blight symptoms in* Hibiscus rosa-sinensis *(A) caused by* Nigrospora sphaerica *(B).*

**Figure 6.** *Anthracnose symptoms in Hibiscus rosa-sinensis (A) caused by Colletotrichum gleosporoides (B).*

acervuli with pink masses of spores emerged on the lesions [26, 27]. *C. gloeosporioides* infect all parts of the plant like twigs, flowers, and fruits irrespective of stages of the crop growth. Symptoms of the infection on the flowers appear as dull brown lesions, and the infected flowers dry off within 48 h after infection. The twigs infected by *C. gloeosporioides* are characterized by the presence of necrotic brown lesions with yellow halo. The necrotic lesions spread gradually toward fruits through peduncle that leads to the development of infection on flowers and fruits. Later, the infected fruits shrink, dry off, and get mummified. After mummification, the infected fruits are

**Figure 7.** *Anthracnose symptoms in* Morinda citrifolia *(A) caused by* Colletotrichum gleosporoides *(B).*

colonized by saprophytic molds like *Aspergillus* and *Penicillium* [26]. Tamil Nadu and Karnataka states in southern India witnessed a severe outbreak of leaf blight, during 2008–2009 by the infection of *A. alternata* [27]. The same pathogen was reported to cause dry fruit rot, which is characterized by the presence of black necrotic sunken spot of 2 to 3 mm diameter on the green unripe fruits [28]. *Pantoea agglomerans* causes soft rot of fruits with the typical symptoms of soft rot of fruits with brown water-soaked lesions on the surface of matured but unripe fruits. The lesion spread quickly within one or two days to the entire fruit, and the infected fruits emit a bad odor. The affected tissue becomes softened and rots subsequently [26]. It is also infected by a wide range of other fungal pathogens such as *Phytopthora* sp. and *Sclerotium rolfisii* (black flag and stem, leaf and fruit blights), *Guignardia morindae* (leaf spot), *Phellinus noxius* (brown root rot), *A. alternata* (dry fruit rot) and *Phytophthora morindae* [29]; *P. agglomerans* (wet fruit rot); and *Collectrotrichum* sp. (anthraconose) [28]. The pathogenic alga, *Cephaleuros minimus* has been reported to cause leaf spot and occurrence of mold infection by *Rhizopus* sp. in the postharvested fruits [28]. Fusarium wilt disease by *Fusarium oxysporum* [30] and phytoplasma disease caused by phytoplasmas (mycoplasma like organisms or MLOs) [31] were also reported. Among these diseases, anthracnose disease by *C. gloeosporioides* was observed in *M. citrifolia* at Bangalore throughout the year with the highest disease index of 13.79% in December and the extent of infection ranged from 10 to 15% (**Figure 7**)*.* Wilt disease on *M. citrifolia* by *F. oxysporum* is prevalent in Bangalore during high humidity conditions and the highest disease index and death of 10% of the plants during September and the extent of infection ranged from 8 to 10% (**Figure 8**).

*Diseases of Medicinal Plants Cultivated in Karnataka and Their Management DOI: http://dx.doi.org/10.5772/intechopen.104632*

**Figure 8.** *Wilt symptoms in* Morinda citrifolia *(A) caused by* Fusarium oxysporum *(B).*

#### **1.7 Velvet bean (***M. pruriens* **(L.) DC.)**

Necrotic crowns and numerous necrotic lesions along the roots and runners of *M. pruriens* caused by *Macrophomina phaseolina* are considered as a serious threat in Nigeria [32]. Foliar fungal diseases (*Cercospora* leaf spot and angular leaf spot, *Phaeoisariopsis griseola*) were also reported in the USA as substantially reducing the biomass of *Mucuna* [33]. Charcoal rot caused by *Modiolula phaseolina* was reported by [34]. Incidence of Leaf blight disease caused by *C. gloeosporioides* occurs in Bangalore in September while in December in Gadag (**Figure 9**). Also, incidence of Rust disease caused by *Uromyces mucunae* was observed in the month of January in Gadag district (**Figure 10**).

#### **1.8 Tulsi (***O. sanctum* **L.)**

There are several diseases that could cause leaf damage leading to yield loss, such as Fusarium wilt (*Fusarium oxysporum f.* sp. *basilicum*) [35]. Other destructive diseases include bacterial leaf spot (*Pseudomonas cichorii*), gray mold (*Botrytis cinerea*), fungal leaf spot by *Alternaria* sp., *Cercospora ocimicola* and *C. gloeosporioides* and damping off or root rot (*Rhizoctonia solani; Pythium* sp.), root rot by *Rhizoctonia solani* and *Pythium* sp. [36]; leaf blight by a species of *Alternaria* [37]; *Gray mold caused* by *Botrytis cinerea* [38]; and powdery mildew caused by *Erysiphe biocellata* [39]. Downy mildew (*Peronospora belbahrii*) is also very destructive and widespread disease in this plant [35].

Wilt disease of Tulsi by *F. oxysporum* is severe during December causing complete mortality in January in Bangalore, and the extent of infection of this disease ranged

#### **Figure 9.**

*Leaf blight symptoms in* Mucuna pruriens *(A) caused by* Colletotrichum gleosporoides *(B).*

**Figure 10.** *Rust symptoms in* Mucuna pruriens *(A) caused by* Uromyces mucunae *(B).*

*Diseases of Medicinal Plants Cultivated in Karnataka and Their Management DOI: http://dx.doi.org/10.5772/intechopen.104632*

**Figure 11.** *Wilt symptoms in* Ocimum sanctum *(A) caused by* Fusarium oxysporum *(B).*

from 80 to 100% with the death of most of the plants (**Figure 11**). Incidence of powdery mildew by *Erysiphe biocellata* occurs in January causing complete mortality in March, and the extent of infection of this disease ranged from 70 to 100% with the death of 100% of the plants (**Figure 12**). Fungal leaf spot disease by *C. gloeosporioides* is noticed in August (**Figure 13**).

#### **1.9 Long pepper (***P. longum* **L.)**

Known to be affected by the number of fungal diseases like showing symptoms of rotting of leaves and vines and by *C. gloeosporioides* [40], necrotic spots and blights on leaves by *Collectotrichum* sp. and *Cercospora* sp. [41]; leaf spot by *Botryodiplodia theobromae*, leaf rot by *Fusarium pallidoroseum* [42] and *Rhizocotonia solani* [40]; Cercospora leaf spot by *C. piperata* [43, 44] and Phytophthora rot by *Phytophthora capsici,* basal wilt by *Sclerotium rolfisii*, Phytophthora Foot rot by *Phytophthora capsici*, and phyllody disease by phytoplasma [40]. In Bangalore, the onset of the anthracnose disease caused by *Colletotrichum boninense* was observed in June with the highest disease index of about 17.5% in September. It gradually decreased during the subsequent months and was found vanish during April and May and the extent of infection of this disease ranged from 29 to 35% (**Figure 14**).

#### **1.10 Crepe jasmine (***T. divaricata/coronaria* **(L.)**

Leaf brown or black spots caused by *Phytophthora citrophthora* in which brown or black spots and patches may be either ragged or circular, with a water-soaked or

**Figure 12.** *Powdery mildew symptoms in* Ocimum sanctum *(A) caused by* Erysiphe biocellata *(B).*

**Figure 13.** *Leaf spot symptoms in* Ocimum sanctum *(A) caused by* Colletotrichum gleosporoides *(B).*

*Diseases of Medicinal Plants Cultivated in Karnataka and Their Management DOI: http://dx.doi.org/10.5772/intechopen.104632*

#### **Figure 14.** *Leaf spot symptoms in* Piper longum *(A) caused by* Colletotrichum boninense *(B).*

**Figure 15.** *Wilt symptoms in Tabernaemontana divaricata (A) caused by Fusarium oxysporum (B).*

**Figure 16.** *Leaf spot symptoms in Tabernaemontana coronaria (A) caused by Colletotrichum boninense (B).*

yellow-edged appearance. Insects, rain, dirty garden tools, or even people can help its spread of this disease [44]. *T. divaricata* is also affected by wilt disease by *Fusarium oxysporum* [45] and rust disease by *Uredo manilensis* [46]. It was found to be affected by *Fusarium oxysporum* with wilting symptoms from September to November, causing death of plants in November and the extent of infection of this disease ranged from 10 to 20% (**Figure 15**). *T. coronaria* with leaf spot disease caused by *Colletotrichum gloeosporioides* was observed from November to January with the highest disease index of 9.7% in the month of January and the extent of infection of this disease ranged from 40 to 50% (**Figure 16**).
