Antifungal Effect of Leaf Extracts on the Groundnut Late Leaf Spot PathogenCercosporidium personatum

Late leaf spot of groundnuts is caused by the fungal pathogen Cercosporidium personatum. Efforts to prevent this disease generally use synthetic fungicides that can pollute the environment. This study aims to identify the fungal pathogen of groundnut late leaf spot and determine the antifungal effect of leaf extract from several plants on leaf spot disease suppression. Late leaf spot pathogen was identified based on hyphae and conidia morphological characteristics. Growth inhibition of leaf extracts from butterfly pea ( Clitoria ternatea ), Mexican sunflower ( Tithonia diversifolia ), basil ( Ocimum gratissimum ), and sugar apple ( Annona squamosa ) at aconcentration of 25% were tested against C. personatum in vitro . The growth and intensity of groundnut disease attacks were assessed for seven weeks by inoculating C. personatum and applied with several leaf extracts. Results showed that the pathogen was identified as C. personatum with conidia characteristics of cylindrical to obclavate, short and slightly curved with four septa, and 35.75 × 7.11 µm in size. The inhibition percentage of C. personatum in vitro reached 94.03% by leaf extract of C. ternatea , 88.56% by T. diversifolia , 87.20% by O. gratissimum , and 84.10% by A. squamosa . Treatment of C. ternatea increased plant height by up to 12.85% and showed the highest reduction of infected leaves by up to 61.53%. C. ternatea leaf extract was found to be the most effective leaf extract to suppress C. personatum infection by 77.94%, while T. diversifolia , O. gratissimum , and A. squamosa reduced disease severity by 70.15%, 65.43%, and 57.76%, respectively.


INTRODUCTION
Late leaf spot due to the infection of Cercosporidium personatum (Berk.& M.A.Curtis) Deighton.is one of the main diseases of groundnut, Arachis hypogaea L. (Sumartini et al., 2020).Cercosporidium personatum generally attacks groundnut leaves in the late growth phase which can decrease productivity (McDonald et al., 1985;Sumartini et al., 2020).In Indonesia, groundnut productivity is relatively low and has tended to decrease in the last five years.The Ministry of Agriculture, Republic of Indonesia (2018) reported that Indonesia's groundnut production in 2014 was 638,896 tons, but production decreased to 512,198 tons in 2018.This decline is believed to be influenced by late leaf spot infestation.
Cercosporidium personatum can infect groundnut leaves resulting in dark brown to black spots accompanied by a circle of thin yellow surrounding them (Meswaet et al., 2021).Therefore, fungicide application is important to suppress the emergence of late leaf spots in groundnuts, but excessive use can cause environmental pollution, health complications, pathogen resistance, and a decrease in agricultural product quality (Andreas et al., 2018).
Plant-based bio fungicides can be used to reduce the negative impact of synthetic fungicides.Parts of plants, such as leaves, are commonly used as ingredients for making natural fungicides.The leaves of several types of plants, such as butterfly pea (Clitoria ternatea L.), Mexican sunflower (Tithonia diversifolia (Hemsl.) A. Gray), basil (Ocimum gratissimum L.), and sugar apple (Annona squamosa L.).Apart from being easy to obtain and cheap, these plant species have been reported to have potential as bio fungicides against fungal pathogenic in plants.These four plant species have been reported to contain similar various antifungal compounds such as alkaloids, saponins, tannins, phenols, terpenoids, and flavonoids (Akinmoladun et al., 2007;Awere et al., 2021;Chakraborty et al., 2017;Kalidindi et al., 2015).Many studies testing these plant species' leaf extracts as bio fungicides against fungal pathogens have been done, such as C. ternatea against Alternaria solani on tomatoes (Suganda et al., 2020), T. diversifolia against Cercospora nicotianae on tobacco plant (Apriyadi et al., 2013), O. gratissimum against Aspergillus niger, A. flavus, and Fusarium solani on peanuts (Adjou et al., 2013), and A. squamosa against Fusarium oxysporum on watermelons or bananas (Purwita et al., 2013).However, the use of these four plant leaf species against C. personatum on groundnuts has not been reported before.
This study aims to determine Clitoria ternatea, Tithonia diversifolia, Ocimum gratissimum, and Annona squamosa leaf extracts' effectiveness as bio fungicides against Cercosporidium personatum in vitro and in vivo on Arachis hypogaea.

MATERIALS AND METHODS
The study was carried out from September 2022 to March 2023 at the Plant Systematics Laboratory and the Sawitsari Study Station, Faculty of Biology, Universitas Gadjah Mada.This study used a completely randomized design (CRD) method consisting of five treatments with five repetitions to test growth inhibition in vitro and six treatments with four repetitions to test the effectiveness of plant leaf extracts in vivo.The treatment consisted of fungal species inoculation (Cercosporidium personatum) with 1.2×10 6 mL -1 conidia density (C), distilled water (P0) used for the control treatment, and the application of various plant leaf extracts.The leaf extracts used were Clitoria ternatea (P1), Tithonia diversifolia (P2), Ocimum gratissimum (P3), and Annona squamosa (P4), at a concentration of 25%.This concentration was selected because concentrations below 25% exhibited low inhibitory effects against several patho-genic fungi (Dongmo et al., 2021;Novianti, 2019;Reviani, 2021;Suganda et al., 2020).The growth inhibition test was carried out on PDA media in vitro with a combination of treatments CP0, CP1, CP2, CP3, and CP4.The effectiveness of plant leaf extracts in vivo used Gajah variety groundnut seeds (A) aged two weeks after planting (WAP) with treatment combination of AP0, ACP0, ACP1, ACP2, ACP3, and ACP4.The growth diameter of C. personatum, disease severity index, the incidence of leaf spots on groundnut leaves, and the plant height of groundnut were observed once a week for seven weeks.

Collection and Identification of Phytopathogenic Fungi
Cercosporidium personatum was isolated from groundnut leaves that showed symptoms of late spotting disease.Isolation was done by cutting 0.5 cm × 0.5 cm leaves, sterilized with 1% sodium hypochlorite (NaOCl) solution for one minute, rinsed with sterile distilled water, and air dried.Each petri dish with 10 ml of Potato Dextrose Agar (PDA) was used, then five pieces of leaves were arranged separately and incubated for seven days at 27 °C (Nayogyani & Kasiamdari, 2022).Cercosporidium personatum mycelia and conidia were identified based on macroscopic and microscopic characteristics.Fungal identification was done using keys by Barnett and Hunter's (1998) and other several credible references.

Preparation of Potentially Antifungal Plant Leaf Extracts
Plant leaves of butterfly pea (Clitoria.ternatea), Mexican sunflower (Tithonia diversifolia), basil (Ocimum gratissimum), and sugar apple (Annona squamosa) were washed, cut into small pieces, and weighed as much as 0.4 kg.Leaf pieces were dried in the oven for 20 min at 80 °C (Chege & Kimaru, 2021) and grinded to obtain leaf simplicia.A total of 25 g of leaf simplicia was added to 75 mL of sterile distilled water to obtain leaf extracts at a concentration of 25%.Extract solutions were homogenized, left for 24 h, and filtered to obtain filtrate (Reviani, 2021).

Growth Inhibition Test of Phytopathogenic Fungi with Plant Leaf Extracts
The in vitro inhibition test was carried out by mixing each plant leaf extract at a concentration of 25% with sterilized PDA media in a Petri dish with a plant extract: PDA media ratio of 1: 10, then the Petri dish was shaken until homogeneous while sterile distilled water mixed with PDA without leaf extract was used for the control (Andriyani & Purwanti, 2019).Cercosporidium personatum hyphae were cut into 5 mm diameter discs and placed in the center of a petri dish containing treatment media.Incubation was carried out for seven days at a temperature of 27 o C and 80% humidity.The growth diameter of C. personatum colonies was measured four times at 1, 3, 5, and 7 Days After Inoculation (DAI).The percentage of growth inhibition of C. personatum colonies was calculated using the Achmad and Suryana (2009) formula as follows: Note: PI = Inhibition percentage of pathogenic fungal growth; D1 = Diameter of pathogenic fungal colonies without leaf extract treatment/control (mm); and D2 = Diameter of pathogenic fungal colonies with leaf extract treatment (mm).

Effectiveness Test of Plant Leaf Extracts against Fungal Infection on Groundnuts
One groundnut plant of Gajah variety was planted in 25 × 25 cm polybag with a planting medium consisting of a mixture of husk charcoal, manure, cocopeat, bamboo leaf humus, and fertile soil for each treatment.Plant arrangement used a completely randomized design (CRD) consisting of six treatments and four repetitions with distances of approximately 50 cm between each plant.Groundnut plants were watered and weeded while fertilizer was not used because nutrients were sufficiently provided by planting medium.Watering was done once a day in the morning until it reached 75% of planting media field capacity (Evita, 2012).
Cercosporidium personatum conidial suspension inoculation was carried out once on each 2 Weeks After Planting (WAP) groundnut seedling.The conidial suspension was prepared by suspending pure isolates of 7 days C. personatum from each Petri dish in 100 mL sterile distilled water at a density of 1.2 × 10 6 mL -1 .As much as 5 mL of C. personatum conidial suspension was sprayed evenly on top and bottom of groundnut leaves, then covered for 24 h in transparent plastic to induce incubation.Groundnut seedlings that have been inoculated with path-ogenic fungi were left for seven days until initial symptoms of C. personatum infection appeared.The first treatment of each leaf extract spray was carried out one week after the inoculation of C. personatum.As much as 5 mL of plant leaf extracts were sprayed once every five days for seven weeks of observation on the top and bottom of the groundnut leaves.
To determine the Cercosporidium personatum severity level, late leaf symptoms on groundnuts were evaluated using the modified 9-point scoring method developed by Subrahmanyam et al. (1995) and modified by Inayati and Yusnawan (2016).Scoring system includes the description of disease symptoms, disease score, and the percentage of leaf area damaged by the disease on groundnuts.The scores used in this study to represent the percentage of damaged leaf area were as follows: 0% = 1; 1−5% = 2; 6−10% = 3; 11−20% = 4; 21−30% = 5; 31−40% = 6; 41−60% = 7; 61−80% = 8; and 81−100% = 9.The percentage of C. personatum disease severity index was calculated using the formula by Putri et al. (2016) as follows: Note: DSI = Disease severity index of the leaf spot (%); n = Number of infected leaves having the same score; v = score for each category of leaf spot; Z = highest score assigned; and N = A total number of leaves observed.
The percentage of disease suppression was carried out to determine the ability of each plant leaf extract to suppress Cercosporidium personatum leaf spot disease which was calculated using the formula by Yulia et al. (2008) as follows: Note: P = Suppression of disease attacks (%); I C = Average disease severity on control (%); and I T = Average disease severity in each plant leaf extract treatment (%).
To determine leaf spot disease incidence on groundnut leaves, the number of infected and total number of groundnut leaves was counted for each leaf extract treatment.The disease incidence value on groundnut leaves was calculated by dividing the number of infected leaves by the total number of leaves.Each leaf extract treatment's efficacy was ISSN 1410-1637 (print), ISSN 2548-4788 (online) 3 measured by the percentage reduction of infected leaves.Furthermore, the average plant height of groundnut was measured weekly over seven weeks to evaluate the potential impact of leaf extract on the plant's growth.Data were analyzed using SPSS Statistics 25 with Analysis of Variance (One Way ANOVA) at α = 5%.If a significant difference occurred between treatments, the analysis was continued using the Duncan Multiple Range Test (DMRT) at α = 5%.

Identification of Phytopathogenic Fungi
The results of isolating the leaves of groundnut plants infected with spots (Figures 1A and 1B) and the growth of the C2 isolate colony aged seven days (Figures 1C and 1D) were obtained.According to Bakhshi and Zare (2020) and Monguillot et al. (2023), the morphology colony of C2 isolate showed similar characteristics to Cercosporidium personatum, which had compact white to orange colonies, irregular to circular shapes, convex elevations with papillate colony surfaces, and smooth-textured mycelium (velvety).
There were similarities in the microscopic characteristics of the C2 isolate with C. personatum according to McDonald et al. (1985) and Meswaet et al. (2021), specifically septate hyphae, branched and pale brown in color (Figure 2A).Conidia are cylindrical to obclavate shape, olivaceous in color, short, and slightly curved.The tip of the conidia was tapered (truncated), while the bases of the conidia were rounded.The conidia of the C2 isolate were 35.75 × 7.11 µm in size and had 4 septa (Figure 2B).
Conidiophores were olivaceous in color, arranged in dense fascicles to form clumps, and unbranched (Figure 2C).These characters showed similarities to C. personatum, which had conidial size ranging from 20 -70 × 5 -9 µm and had 2 -6 septa (McDonald et al., 1985;Meswaet et al., 2021).The morphological characteristics are important for distinguishing fungal species and species identification (Nayogyani & Kasiamdari, 2022).Clitoria ternatea leaf extract had the most significant inhibitory effect on the growth of Cercosporidium personatum (Table 1).The highest to lowest C. personatum inhibition at 7 Days After Inoculation (DAI) were shown by C. ternatea (94.03%),Tithonia 5 diversifolia (88.56%),Ocimum gratissimum (87.20%), and Annona squamosa (84.10%).Clitoria ternatea is believed to possess antifungal properties that inhibit C. personatum growth compared to the other three plant leaf extract treatments.C. ternatea contains various secondary metabolites, including alkaloids, carbohydrates, phenols, flavonoids, saponins, tannins, terpenoids, and quinones, (Chakraborty et al., 2017).Although the type and quantity of phytochemical content were not analyzed in this study, it is likely that the presence of antifungal compounds plays a significant role in the inhibitory power produced.

Growth inhibition of
All leaf extract treatments showed significantly different, had stable values, and produced relatively high percentage of inhibition.Suganda et al. (2020) reported that Clitoria ternatea leaf extract at a concentration of 9% was able to inhibit Alternaria solani Note: DAI = Days After Inoculation.Numbers followed by the same letter in each column are not significantly different based on Duncan's Multiple Range Test (DMRT) at α = 5%.Cercosporidium personatum growth inhibitory in this study was possible due to the effect of antifungal compounds contained in each plant's leaves.The four types of plant leaves species were reported to contain the same phytochemical compounds, specifically alkaloids, saponins, tannins, phenols, terpenoids, and flavonoids (Akinmoladun et al., 2007;Kalidindi et al., 2015;Chakraborty et al., 2017;Awere et al., 2021).These phytochemical compounds were reported to disrupt peptidoglycan wall constituent components, inhibiting nucleic acid synthesis (Ornay et al., 2017), causing leakage of intracellular material, interfering with nutrient absorption and metabolic processes in fungi (Septiadi et al., 2013), and inhibit the synthesis of chitin during cell walls formation (Watson & Preedy, 2007).

Effectiveness Test of Plant Leaf Extracts against Fungal Infection on Arachis hypogaea
The results showed that groundnut plants began to be infected with Cercosporidium personatum leaf spot disease at the age of 4 weeks after planting (WAP) or 2 weeks after inoculation (WAI).These results were similar to Saleh (2002) who revealed that C. personatum can attack groundnuts at the age of 3-5 WAP.The observed symptoms of C. personatum leaf spot disease was also reported by Sumartini (2008), Meswaet et al. (2021), andMc-Donald et al. (1985), who stated that there were spots with irregular shapes to circles, dark brown to black in color, and there was a thin yellow halo that encircling the spot.The spots that form on the adaxial side of the leaf were dark brown in color, while the spots on the abaxial side were black because it was thought to be the site of sporulation.
Disease severity in each treatment showed significantly different values every week until seven WAI (Figure 4).It was found that the four plant leaf species suppressed Cercosporidium personatum disease severity at 3 WAI and continued until the end of the observation.On the seventh week, the control treatment (C.p.) had the highest disease severity value of 26.25%.Disease severity of C. personatum treated by leaf extracts of Clitoria ternatea, Tithonia diversifolia, Ocimum gratissimum, and Annona squamosa had lower values of 5.79%, 7.82%, 9.07%, and 11.10% respectively at 7 WAI than the control treatment.Leaf extracts used in this study had a better inhibitory effects against C. personatum leaf spot disease on groundnuts because they showed lower disease severity value than the previous study.Apriyadi et al. (2013) reported that T. diversifolia leaf extract at a concentration of 75 g/L was able to control the development of Cercospora nicotianae in tobacco plants with a disease severity index of 9.62% at 65 days after planting (DAP).To this date, no data is available regarding the potency of C. ternatea, O. gratissimum, and A. squamosa leaf extracts against C. personatum.
Cercosporidium personatum leaf spot suppression by each treatment showed that leaf extract treatments resulted in significantly different values at 3 WAI until 7 WAI (Table 2).At the end of the observation, Clitoria ternatea leaf extract showed the highest disease severity suppression at 77.94%, followed by Tithonia diversifolia (70.15%),Ocimum gratissimum (65.43%), and Annona squamosa (57.76%).Based on previous research, the inhibition value of leaf extract against C. personatum in vivo was different from the results of inhibition in vitro.This difference can occur and is thought to be influenced by environmental factors such as temperature and humidity in the in vivo test.The value of disease inhibition will appear smaller when leaf spot disease can infect its host more quickly with the support of temperature and humidity.According to Sumartini et al. (2020), the emergence of late leaf spot disease in Indonesia is strongly supported by the tropical climate factor, which tends to be humid with a mini-mum, optimal, and maximum temperature range of 10 °C, 25 °C, and 31 °C.McDonald et al. (1985) also revealed that air temperatures ranging between 25− 30 °C with high humidity support leaf spot disease emergence in groundnuts.Furthermore, groundnut leaf resistance against C. personatum infection plays a crucial role in determining the disease inhibition value.According to Sunkad and Kulkarni (2006), the resistance levels of groundnuts against leaf spot disease can be determined based on their morphological characteristics, including having a high number and large size of stomata, low number of epidermal cells, thick cuticle tissue and epidermis layers, and thicker wax layer on reproductive phase.This study focused on the Gajah variety of groundnuts, which is known to be vulnerable to C. personatum leaf spot.Consequently, the leaf extract inhibition value in vivo was relatively lower than the in vitro test.

7
Results indicate leaf extracts had the potential as an antifungal to suppress Cercosporidium personatum leaf spot disease on groundnuts.The high disease suppression by Clitoria ternatea leaf extract was possible due to the effect of antifungal compounds contained in the leaves, such as alkaloids, carbohydrates, phenols, flavonoids, saponins, tannins, terpenoids, and quinones (Chakraborty et al., 2017).Different disease suppression values in each treatment can also be caused by the presence of specific compounds such as essential oils.It was reported that C. ternatea leaves contain several kaempferol compounds, such as kaempferol-3-monoglucoside, kaempferol-3-rutinoside, kaempferol-3-neohesperi doside, kaempferol-3-O-rhamnosyl-glucoside, and kaempferol-3-O-rhamnosyl-galactoside (Mukherjee et al., 2008).The role of kaempferol had been tested and previously reported to have a significant anti-  fungal activity to inhibit some fungal growth (Galeotti et al., 2008).It is imperative to conduct further research studies to establish whether the kaempferol compound exhibits a similar inhibitory effect on the growth of Cercosporidium personatum in Clitoria ternatea leaves.This critical inquiry will aid in establishing the role of kaempferol in the plant's antifungal properties, providing crucial insights into the development of more effective fungicides.However, it is strongly suspected that the presence of antifungal phytochemicals in C. personatum influences the disease-suppressing ability.Based on several references, it was previously found that the leaf extracts contained some phytochemical compounds (Akinmoladun et al., 2007;Awere et al., 2021;Chakraborty et al., 2017;Kalidindi et al., 2015), especially terpenoids.Terpenoids were one of the secondary metabolites that were reported to inhibit the growth of fungi by interfering with the growth, development, and formation of fungal spores (Lutfiyanti et al., 2012).The application of plant leaf extracts at a concentration of 25% can reduce the infected leaves (Table 3).The leaves of groundnut plants began to be infected with Cercosporidium personatum spot disease at 2 WAI until 7 WAI.Plant leaf extract treatments reduced the percentage of infected leaves from 3 WAI.At the end of the observation, percentage of infected leaves with the highest value was shown in the control treatment (C.personatum) of 18.30%.Percentage of infected leaves with the lowest to the highest value at the end of the observation sequentially was Clitoria ternatea leaf extract (7.04%), Tithonia diversifolia (7.71%), Ocimum gratissimum (8.54%), and Annona squamosa (10.46%) at 7 WAI.From these results, C. ternatea leaf extract produced the lowest percentage of infected leaves compared to other treatments possibly because of antifungal compounds (Chakraborty et al., 2017), which was more effective in inhibiting fungal infection.
The four plant leaf extracts with a concentration of 25% were effective in reducing the number of leaves infected with Cercosporidium personatum leaf spot based on the decrease in the percentage of infected leaves (DP).At the 7 WAI, Clitoria ternatea leaf extract could reduce the highest percentage of infected leaves by 61.53%, followed by Tithonia diversifolia (57.84%),Ocimum gratissimum (53.34%), and Annona squamosa (42.82%).To this date, there are no studies before that reveal the percentage value of leaves infected with disease produced by four plant leaf extracts against C. personatum, this study can provide information about the potential of four plant leaf extracts to reduce percentage of infected leaves in groundnut plants.
Based on Figure 5, the plant height from each treatment showed significantly different values every week, except at 3 and 4 WAI.It appeared that each plant leaf extract treatment resulted in a higher average plant height compared to the negative control.That was appropriate with Korwa et al. (2009), where untreated groundnut plants affected by Cercospora sp.showed lower plant height compared to the results obtained in this study.Groundnut plant height produced by leaf extract treatments at 7 WAI ranged between 56.25−62.33cm, whereas Korwa et al. (2009) only resulted in heights ranging between 38−48.8cm at the age of 10 WAP.The application of leaf extract in this study produced higher height growth compared to control plants.The height of the groundnut plant can also be affected by several other factors, such as plant variety, type of planting media, availability of nutrients/nutrients, growth regulators, light intensity, competition with weeds, and spacing (Kasno et al., 2015).
The leaf extracts treatment resulted in plant heights that were not significantly different from each other at the end of this study.The average plant height produced by each extract treatment in the seventh week with the largest to smallest values sequentially was Clitoria ternatea (62.33 cm), Tithonia diversifolia (61.98 cm), Ocimum gratissimum (61.00 cm), and Annona squamosa (56.25 cm).Clitoria ternatea leaf extract was found to increase the plant height by 12.85%, T. diversifolia by 12.22%, O. gratissimum by 10.45%, and A. squamosa by 1.85%.In addition to their potential to inhibit the attack of the fungal disease of Cercosporidium personatum, leaf extracts besides being able to be used as natural fungicides on groundnut plants were also safe on cultivated crops because they do not have negative impact on plant growth.This result is in accordance with Sudarmo (2005) where plant-based fungicides can inhibit disease development and was also safe for humans, the environment, and agricultural plants because they can easily decompose and leave no residue on agricultural products.

CONCLUSIONS
Results showed that treatments of four leaf extracts had the potential as natural fungicides against leaf spot disease caused by Cercosporidium personatum on groundnuts.Leaf extract of Clitoria ternatea showed the highest growth inhibition of C. personatum in vitro by 94.03%.Leaf extract of C. ternatea was found to be the most effective leaf extract to suppress leaf spot disease on groundnut plants by 77.94%, followed by Tithonia diversifolia, Ocimum gratissimum, and Annona squamosa by 70.15%, 65.43%, and 57.76%, respectively.Leaf extract of C. ternatea treatment produced the lowest disease severity value of 5.79% while also increased plant height up to 12.85%, and reduced the most optimal percentage of infected leaves up to 61.53%.

ACKNOWLEDGEMENT
The authors would like to thank staffs of Plant Systematics Laboratory and Sawit Sari Research Station, Faculty of Biology, Universitas Gadjah Mada for assisting during these experiments.The authors would also like to thank the Faculty of Biology, Figure 1.Symptom of leaf spot and pure culture of Cercosporidium personatum: leaf spots on groundnut leaves (A); leaf spot under a stereo microscope at 4× magnification (B); the colony of C2 isolates aged seven days on PDA media, front view (C) and back view (D)

Table 1
. Effect of leaf extracts of several plants at a concentration of 25% in PDA media on growth inhibition of Cercosporidium personatum in vitro at 7 days after inoculation Figure 3. Growth of Cercosporidium personatum colonies in vitro on the 7 th day after incubation on PDA media treated by leaf extract at a concentration of 25%, control (no leaf extract) (A); Clitoria ternatea (B); Tithonia diversifolia (C); Ocimum gratissimum (D); and Annona squamosa (E)

Table 2 .
Percentage of Cercosporidium personatum leaf spot disease suppression on groundnuts after plant leaf extract treatments at a concentration of 25% during seven weeks after inoculation (WAI) Note: WAI = weeks after inoculation.Numbers followed by the same letter in each column are not significantly different based on Duncan's Multiple Range Test (DMRT) at α = 5%.

Table 3 .
The incidence of leaf spot disease on groundnut leaves artificially inoculated with Cercosporidium personatum and treated with leaf extracts at a concentration of 25% at seven weeks after inoculation (WAI) Note: WAI = weeks after inoculation, DP = Decreasing Percentage of Infected Leaves.