Chapter 2 Review of Literature
4 REVIEW OF LITERATURE Sunflower (Helianthus annus I.) is a major oilseed crop in India, particularly in Karnataka and Maharashtra. Concomitant with increase in sunflower production, there has been increased incidence and severity of its diseases. Alternaria leaf blight caused by Alternaria helianthi (Hansf.) Tubaki and Nishihara is an important disease of sunflower crop in India particularly in the peninsular part of the country on monsoon crop under late sown condition. This disease is reported to cause 80% loss (Balasubrahmanyam and Kolte, 1980; Hiremath et al, 1990). Of late, the farmers of West Bengal cultivate sunflower in the Rabi season by changing crop rotation and crop pattern to get more economic return. Different works have been done regarding the disease and its management in India elsewhere. But the linearization of disease progress curve is essential to determine the epidemic spread to project future disease and to estimate initial disease for better management (Bergar, 1981). Among the various reasons attributed to low productivity, diseases are a major constraint in India (S.J. Allen, 1982). Alternaria leaf blight is considered a destructive disease. It is widely distributed wherever the crop is grown. A reduction in seed and oil yield by 27 to 80 and 17 to 33 per cent respectively has been reported. A negative correlation has been established between an increase in disease intensity and yield components and oil content. The most affected components due to disease are number of seeds per head, followed by the seed yield per plant. The disease also affects the quality of sunflower seeds by affecting germination and initial vigour of the seedlings. In sunflower development programme in India, it has become amply clear that incorporation of resistance of downy mildew and rust diseases into high yielding hybrids and cultivars is possible. The literature pertaining to above aspects is presented here. 2.1 History of this disease Hansford (1943) first reported the fungus causing leaf spot of sunflower from Uganda and described the causal organism as Helminthosporium helianthi Hansford. Tubaki and Nishihara (1969) isolated this fungus from diseased leaves of cultivated sunflower and after comparative study with Hansford s type specimen Helminthosporium helianthi, it was concluded that, both fungi were same and re-described as Alternaria helianthi due to presence of longitudinal septa. The first record of this disease in India was simultaneously reported by Narain and Saksena (1981) and Kolte and Mukhopadhyay (1973) from Uttar Pradesh and subsequently by Anil Kumar et al. (1974) from Karnataka.
5 2.2 Distribution and economic importance The Alternaria leaf blight of sunflower has been reported from India and elsewhere (Acimovic, 1969; Shane et al., 1981; Herr and Lipps, 1981; Kolte, 1985; Sackston, 1988). The pathogen is capable of causing the disease over a wide range of atmospheric temperature and thus constitutes a potential threat to sunflower producing regions of the world (Abraham et al., 1976; Islam and Maric 1980; Sackston, 1988). Reddy and Gupta (1977) reported the loss in yield ranging from 11.3 to 73.2 per cent. Significant reduction in the yield parameters viz., height, stem girth, head diameter, number of seeds per head, test weight, yield and oil percentage were observed (Mathur et al., 1978; Balasubramanyam and Kolte, 1980b). The pathogen affected more than 280 ha of sunflower in June 1980 in Minnesota (Shane et al., 1981). Hiremath et al. (1990) reported 95 to 100 per cent incidence of this disease in north Karnataka. Borkar and Patil (1995) reported severity of this disease to the extent of 52 to 85 per cent in three year of study. 2.3 Symptoms The Alternaria leaf blight is known to infect all aerial parts of plant viz., leaf, petiole, stem, floral parts and seeds. Initially, the disease appears in the form of small, scattered brown spots on the leaf lamina. Later, these spots increase in size and coalesce covering larger leaf area (1 to 2.5 cm in diameter), with dark brown margin and yellow halo. Linear necrotic lesions also appear on stem, petioles and sepals. In severe cases the head and seeds also get infected (Tubaki and Nishihara, 1969; Narain and Saksena, 1973; Kolte and Mukhopadhyay, 1973 and Anil Kumar et al., 1974). Severe infection of Alternaria blight on leaf, stem, petiole and inflorescence including petals were described by many workers (Mukewar et al., 1980; Balasubramanyam and Kolte, 1980a,b. Hiremath et al. (1990) observed cracking of stem and petioles along with other symptoms is severely infected plants. 2.4 The pathogen Tubaki and Nishihara (1969) described the morphology of the pathogen mycelium as olivaceous brown, septate, smooth and branched. The conidiophores are cylindrical, attered or gregarious, pale gray to yellow, straight or curved, up to five septa, geniculate, single or branched with a size of 25-80 x 8-11 µm. The conidia, produced singly on conidiophores were cylindrical to long ellipsoidal, straight or slightly curved, pale grey yellow to pale brown in colour with one to eleven transverse septa and one to three longitudinal septa. The conidia were predominantly constricted at transverse septa and measured 40-110 x 13-28 µm.
6 2.5 Survey for Alternaria blight of sunflower Hiremath et al. (1990) reported widespread occurrence of Alternaria leaf blight on sunflower during Kharif 1987 from north Karnataka. Regular surveys conducted by AICRP (Sunflower) Centers revealed that Alternaria blight was severe during Kharif. In Akola the incidence was upto 30 percent during 1996 to 2000. However the incidence was less than ten percent during 2002-03 and 2004-05. In Coimbatore the disease incidence was moderate (upto 25%) during 1996 to 2000, while it was severe during 2001 to 2005. Similarly in Bangalore, Latur and Raichur the incidence ranged between five to thirty percent, five to thirty five percent and nine to sixty percent respectively during 1996 to 2004 (Anon., 1996; Anon., 1997; Anon., 1998; 1999a; Anon., 2000; Anon., 2001; Anon., 2002a; Anon., 2003; Anon., 2004; Anon., 2005 and Anon., 2006). 2.6 Epidemiological Studies Benagi et. al.(1998) developed autoregressive model for late leaf spot of groundnut by incorporating one variable pertaining to environmental factors at a time viz., RH-I, II, maximum and minimum temperature. It was noticed that RH-I and II of Kharif 1993 and RH- I, maximum temperature of Kharif, 1994 were found to have negative relationship with the disease severity. The logistic model was also developed for understanding the development of late leaf spot during Kharif 1993 and 1994. 2.6.1 Effect of sowing dated on the incidence of disease Venkataramana et al. (1995) conducted experiment on date of sowing taking parental lines of sunflower. They observed that Alternaria leaf blight is a serious problem during late Kharif. The parental lines RHA-6D-1 and CMS-234A were less susceptible while MRHA-1 was found to be more susceptible to this disease. Amaresh (2000) reported highest incidence of Alternaria leaf blight when crop was sown on second fortnight of July and first fortnight of August. Mesta et al. (2003) reported that the Alternaria leaf blight of sunflower was severe in July sown crop and it reduced during further sowings. Rao (2006) reported maximum blight incidence in July second fortnight shown crop and least in December sown crop. Allen et al. (1983a) reported that, the amount of chlorosis induced by Alternaria helianthi was greatest in plants that were inoculated at the vegetative or budding stage. Sunflower plants were more susceptible to infection by Alternaria helianthi during the anthesisand seed filling stages of growth (Anilkumar et al., 1974; Anilkumar et al., 1976; Islam et al., 1976; Allen et al., 1983b, Jeffery et al., 1984).
7 Disease intensity had a negative and significant correlation with air temperature and sunshine hours, whereas for relative humidity a positive and significant correlation was found. The disease was successfully predicted by using weather parameters. 2.6.2. Relation between weather parameters and disease development Acimovic (1969) reported that Alternaria helianthi is pathogenic to Leucanthem vulgare Lam. and Ricinus communis L. The pathogen was isolated Xanthium pungens Waller and Xanthium spinosum L. which were the common weeds in sunflower growing in Australia. It is isolated from safflower (Carthamus tinctorius L.) also (Allen et al., 1983 and Patil et al., 1992) Alternaria helianthi is a serious leaf spot pathogen of sunflower crop especially during kharif session i.e., monsoon grown sunflower crop (Kolte and Mukhopadhyay, 1973; Narain and Saksena, 1981; Agarwal et al., 1979; Herr and Lipps, 1981; Allen et al., 1983a, b). Acimovic (1974) reported that the minimum, optimum and maximum temperature for infection were about 5 0 C, 30 0 C and 35-40 0 C respectively. The generation time varied from 13 days at 5 0 C, two days at 20 0 C, 25 0 C and 30 0 C and three days at 35 0 C. the sporulation occurred between 5 0 C, 10 0 C and 30 0 C were smaller in size, had fewer septa than those formed at 15 0 C, 20 0 C and 25 0 C. Anilkumar et al. (1976) noticed that the warm humid conditions were highly congenial for disease build up. Under prolonged warm humid conditions, even the highly resistant helianthus agrophyllus a wild relative of cultivated sunflower could also get infected by Alternaria helianthi. Islam and Maric (1980) reported that, Alternaria helianthi grew at temperature range of 4 0 C to 32 0 C, with maximum growth at 20 0 C to 28 0 C, and optimum at 26 0 C. They also found that sporulation was poor below 16 0 C and abundant between 20 0 C and 28 0 C. The minimum dew period required for infection was 12 hrs (Islam et al., 1976). However, Bhaskaran and Kandaswamy (1980) noticed increased incidence of Alternaria helianthi with increase in number of days of low temperature (<20 0 C) Hiremath et al. (1990) reported positive correlation between disease severity and relative humidity. The high humid conditions prevailed during rainy season caused disease epidemics in many parts of Karnataka. Borkar and Patil (1995) studied the weather in relation to Alternaria leaf blight disease development in Maharashtra. Temperature of 25.9 0 C to 33.7 0 C with relative humidity of 89 to 95 percent favoured disease development. They further reported that development of the disease was influenced by rainfall.
8 2.6.3. Perpetuation of pathogen Islam et al. (1976) reported that, under natural conditions the important source of inoculums was diseased plant debris. They also reported that, conidia did not retain viability in winter but the mycelium survived to produce conidia. Bhaskaran and Kandaswamy (1980) reported that the fungus Alternaria helianthi remained in plants debris for 22 weeks, which was left on soil surface continuously dry. Alternaria helianthi was reisolated from 12 month old sunflower crop debris that over wintered in the field which showed its ability to survive during off season (Lipps and Herr, 1981; Shane et al., 1995 and Appaji, 1995). Agarwal et al. (1976) studied the seed mycoflora of fourteen varieties of sunflower and recorded Botrytis cinerea, Sclerotinia sclerotiarum and Verticillium sp. Ramegowda (1980) recorded species of Alternaria, Asoergillus, Fusarium, Penicillum and Rhizopus on stored sunflower seeds. Varietal differences were also seen in this study. Bhaskaran and Kandaswamy (1980), Sackston (1981), Lipps and Herr (1981), Morris et al. (1983), Shane et al.(1981) and Herr and Lipps, (1982), reported the internal seed borne nature of Alternaria helianthi in sunflower seed and it was 22.9 percent seed transmissible. Alternaria helianthi was detected in all the parts of the sunflower seeds showing more than 65 percent in endosperm and 25-30 percent in embryo. Hiremath et al. (1993) also reported that Alternaria helianthi was internally seed borne in sunflower seeds. Prasad and Kulshrestha(1996) showed that, out of sixteen samples of healthy seeds, five categories showed infection. Pre treatment of seeds with sodium hydrochloride resulted in drastic reduction in infection levels. Presence of Alternaria helianthi was detected in pericarp, endosperm and embryo by employing component plating technique. When infected seeds were sown, seedling blight was observed indicating the role of seed borne inoculum. Prasad and Kulshrestha (1999) observed sunflower seeds naturally infected and artificially inoculated with Alternaria helianthi showed 32.8 and 19.0 percent reduction in germination respectively. Shoot and root lengths of seedlings were also reduced in both cases. The vigour index was very low in naturally infected seeds (400.0). artificially inoculated seed recorded a vigour index of 535.5 whereas in control it was 1799.8. Mesta et al. (2006) reported eight fungi viz., Alternaria alternate, Alternaria helianthi, Fusarium sp., Curvularia sp., Aspergillus sp., Rhizopus sp., Mucor sp. and Cladosporium sp. occurring on seeds on sunflower. Rao (2006) observed Alternaria alternate, Alternaria helianthi, Rhizoctonia sp., Aspergillus sp., Rhizopus sp. and Mucor sp. occurring on seeds collected from different regions of Karnataka.
9 2.7 Effect of nitrogen, phosphorus and potassium on the foliar disease caused by Alternaria Nutrition to the plant is one of the most important factor for crop production that affect growth, yield quality of the produce and also increase or decrease the pathogen population in crop rhizosphere that cause damage to the plant. The response of sunflower crops to nitrogen, phosphorus and potassium nutrition varies according to the type of land for cultivation, soil type as well as fertility status of soil and environmental conditions. Awad et al. (1978) reported that application of nitrogen fertilizers at twice the normal level increased the increased the incidence of purple leaf blotch of onion caused by Alternaria porri. He further stated that the effect of calcium superphosphate reduced it but the effect of potassium was variable. Mondal et al. (1989) reported that higher doses of nitrogen (150 or 200 kg urea/ hectare) in combination with higher doses of phosphorus (triple super phosphate) and with 80 kg murate of potash/hectare reduced the incidence of purple blotch of onion caused by Alternaria porri. Dasgupta et al. (1991) observed that the higher application of nitrogen fertilizers reduced the disease incidence of Alternaria blight caused by Alternaria brassicola on Indian mustard, Bhargava and Singh (1992) observed that the lower doses of urea fertilizer induced higher disease intensities than the other forms of nitrogen (ammonium sulphate and calcium ammonium nitrate) in case of blight of bottle gourd (Lagenaria siceraria) caused by Alternaria cucumerina. According to Singh et al. (1992) the severity of white leaf spot of cabbage caused by Alternaria brassicola increased with increasing application of nitrogen. He further stated that addition of potassium decreased disease severity while phosphorus had no significant effect on disease severity. Sharma et al. (1994) observed that the severity of black spot disease of oil seed rape (Brassica campestris L.) caused by Alternaria brassicae was significantly greater (36-48%) on plants grown in ground treated with nitrogen and phosphorus (N @ 90kg/ha and P @ 40kg/ha) in decreasing the severity of black spot disease was increasingly more pronounced than the effects of PK (P @ 40kg/ha and K@ 40kg/ha), NPK (40 kg/ha). The decrease in severity of BSD due to potassium was due to increased production of phenolics in plants, which inhibited conidial germination and decreased sporulation of Alternaria brassicae.
10 Barcley et al. (1972) observed that high nitrogen and low phosphorus levels significantly reduced the incidence of Alternaria solani. He further suggested that this combination of nutrients may be related to the disease resistance in plants extending the period of meristimatic activity, thus enabling the plant to wall off infection. According to Soltanpour and Harrison (1974) there is an interrelation between nitrogen and phosphorus fertilization on early blight of potato caused by Alternaria solani. Iacob (1979) observed that the application of nitrogen, phosphorus and potassium fertilizers have considerable effects on the development of Alternaria solani on potato. Mackenzie (1981) reported that increased nitrogen application reduced the apparent infection rate of potato early blight (Alternaria solani) and final amount of disease. Bedi and Dhiman (1986) observed that normal doses of phosphorus and potassium decreased the susceptibility of potato plants towards Alternaria solani, but the double doses of phosphorus and potassium increased the susceptibility of potato towards Alternaria solani. He further stated that normal doses of nitrogen or phosphorus increased susceptibility but this effect was reversed with double doses of nitrogen and phosphorus. Kumar et al. (1986) reported that the application of balanced fertilizer (100 kg nitrogen + 125 kg phosphorus and 125 kg potassium per ha) produced the highest yield and reduced the Alternaria solani significantly in case of potato. Blackinski et al. (1996) reported that the foliar application of urea or potassium nitrate does not affect the response of potato towards Alternaria solani. Huang et al. (1999) observed that the application of potassium fertilizer increased plant resistance to tomato early blight (Alternaria solani) and decreased the disease incidence and disease index. Sharma and Kolte, S.J. (1994) studied on the effect of soil applied NPK fertilizers on severity of black spot disease (Alternaria brassicae) and yield of oil seed rape. The effect of soil application of eight combinations of NPK fertilizers on the security of black spot disease (BSD) caused by Alternaria brassicae (Sacc). Berk., and yield of short duration oilseed rape (Brassica compestris L.) were investigated under both pot and field conditions in 1987-88. 1988-89 and 1990-91. The severity of BSD was significantly greater (36-48%) on plants grown in ground treated with NP (N @ 90 kg/ha + P @ 40 kg/ha) applied as urea and super phosphate respectively than on plants from the unfertilized control (NoPoKo) (0). However, the severity of BSD was significantly smaller (25-33%) when K (40 kg/ha) was applied as murate of potash than in plants from control and NP treatments. The effect of NK ( N @ 90kg/ha + K @ 40kg/ha) in decreasing the severity of BSD was increasingly the more
11 pronounced than the effect of PK (P@ 40 kg/ha + K@ 40 kg/ha), NP and K (40 kg/ha) applications. The decrease in severity of BSD due to K was due to increased production of plants of phenolics which inhibited conidial germination and decreased sporulation of Alternaria brassicae. The decreased in severity of BSD due to NPK application gave constantly increased seed yield 68% more than those of control and the other treatments. The K fertilized plants also showed increased resistance to lodging, increased 1000-seed weight and decreased seed infection. Seeds obtain from K fertilized plants showed good seed germinability and vigorous seedling growth. Barclay et al. (1973); Soltanpour et al. (1974); Mackenzie (9181) showed that high N concentration have decreased the severity of early blight of potatoes. Warncke (1996) noted an increase in foliar disease in carrot plants given low N levels. 2.8 Assessment of disease severity 2.8.1 Leaf spot and rust disease Noriega-Cantu et. al. (2000) developed a scale for the field assessment of foliar diseases particularly late and early leaf spot and rust scored with seven classes pictorial scale of severity: 1 = 0 0.5% leaf area damage 2 = 0.5 3% leaf area damage 3 = 3 7% leaf area damage 4 = 7 15% leaf area damage 5 = 15 33% leaf area damage 6 = 33 70% leaf area damage 7 = 70 100% leaf area damage 2.8.2 Leaf spot disease Rapid field assessment of leaf spots can be done using a disease index standard area diagrams or hand-held radiometers. Two typical scales that have been used for late leaf spot are the ICRISAT, 1 9 scale and the Florida 1 10 scale. In field assessment of leaf spots, it is important to define the developmental stage of the crop. ICRISAT scale for assessment of late leaf spot 1 = No disease 2 = Few, small necrotic spots on older leaves. 3 = Small spots, mainly on older leaves, sparse sporulation. 4 = Many spots, mostly on lower and middle leaves, disease evident.
12 5 = Spots easily seen on lower and middle leaves, moderably sporulating yellowing and defoliation of some lower leaves. 6 = As rating 5 but spots heavily sporulating. 7 = Disease easily seen from a distance; spots present all over the plant; lower and middle leaves defoliating 8 = As rating 7 but defoliation is more severe. 9 = Plants severely affected, 50 100 percent defoliation. 2.9 Prediction the course of an epidemic Vanderplank (1963) first attempted a mathematical analysis for forecasting plant disease epidemics in apple scab and computer simulations were done by Waggoner and Horsfall (1969) and many others subsequently. Vanderplank (1982) also pointed out that the apparent infection rate estimated for full period not reflects the seasonal variation. Some growth equations were also given for disease progression by Analytis (1973, 1979), Kranz (1974b), Hau and Kranz (1977), Berger (1981) and Luke & Berger (1982). Some research workers also tried to develop new equations for analysis of disease progress (Jowett et. al. 1974; Pennypacker et. al. 1980). Hau et. al. (1985) also used some statistical growth function for description of plant disease epidemics. Richards (1959) and Analytis (1973) explained two models, logistic and gompertz for plant disease forecasting. Schrodter and Ullrich (1965) first introduced a realistic model for late blight of potato disease epidemics. In plant disease epidemics multiple regression analysis (MRA) was introduced first by Kranz (1968b), Royle and Thomas (1972) and Analytis (1973). Butt and Royle (1974) described merits and demerits of MRA in plant disease epidemiology. Zadoks and Schein (1979) reported that apparent infection rate was a useful tool in comparative epidemiology of a single pathosystem. Fry (1987) used some equations to predict the required effect for disease management to achieve a desired degree of disease suppression. Amaresh (2000) developed prediction models of Alternaria blight of sunflower using autoregressive and logistic equations. The autoregressive model was given as Y t-1 =1,233 Y t with autoregressive co-efficient of 0.98, whereas logistic model was given as Y t = 100/1+e with R=0.97 2.8.1 Prediction model of Alternaria leaf blight epidemic Several research workers attempted to develop some workable forecasting models in relation to weather parameters. Wang et. al. (1987) studied a new Gompertz derived model to describe the relationship between disease severity and incidence. They also showed that the Gompertz derived model had a stronger capacity in fitting data with good results in most
13 cases. Savary and Zadoks (1992) reported that the results of analysis of variance were compared with the results of multiple regression analyses. Davis et. al. (1993) used the Von Bertalarffy and Richards equation to develop all modes of late leaf spot of groundnut. Aquino et. al. (1995) observed that both apparent infection rate and Area under disease progress curve (AUDPC) values were highly correlated with latent period and maximum percentage of lesions. Lannou and Savary (1992) used the geo-statistical techniques, which were applied to describe and compare the spatial patterns of epidemics of early and late leaf spot of peanut. Recently, Sinha et. al. (2002) provided an overview to understand the growth dynamics, nonlinear mechanistic growth models like monomolecular, logistic and gompertz models to the disease epidemics.