**4.4 Curvularia leaf spot (CLS)**

This is a foliar disease and caused by *Curvularia lunata,* (**Figure 4**) also common in many plant species in tropical, subtropical as well as sometimes in temperate regions. Earlier in 2000, in Indian subcontinent this disease observed in traces from most of the places. Now a days this disease (**Figure 5**) recorded in severe condition from some pockets of Rajasthan from Uttarakhand (Haridwar, Dehradun and Kashipur). Polysora rust and Curvularia leaf spot (CLS) are emerging as a potential threat in Karnataka & Rajasthan respectively. Hot and humid climate favor the development of disease during flowering to grain filling stage.

**Figure 3.** *Field view and symptoms of PFSR.*

*The Impact of Climate Change on Changing Pattern of Maize Diseases in Indian Subcontinent... DOI: http://dx.doi.org/10.5772/intechopen.101053*

**Figure 5.** *Disease spectrum of Curvularia leaf spot from year 2005–2014 (source: [40]).*

## **5. Declining of major diseases of maize with time due to climate change**

### **5.1 Pythium stalk rots**

During the past, in early 1980s Pythium stalk rot (**Figure 6**) was in severe condition and use to cause extensive damage to the crop in the lowlands of Indian subcontinent. This disease caused by *Pythium aphanidermatum*, temperature and relative humidity are the main factors to determine severity of the disease. Most favorable condition for the disease development is high temperature range 30–35°C with relative humidity of 80–100%. In past decades the disease was considered as major disease, now over the year passed the incidence/occurrence of the disease reduced [40] due to altered precipitation, various changes in this pathogens may occurred

**Figure 6.** *Pythium stalk rot.*

which in general include coincidence of pathogen lifecycle events with host plant stages and/or natural antagonists/synergists. Therefore regional precipitation and distribution patterns led to unfavorable condition for development of sporulation for secondary infection. However, projected warmer and drier summers may hinder most fungal diseases, and finally slow down or completely inhibit disease progress of other foliar diseases. As a result the regional distribution patterns of this diseases may be modified and stated to infect *rabi*/winter maize due warming effect.
