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Abstract Pod rot disease of peanut is a serious disease worldwide. it occurs on fruits that develop below ground. Diseased plants do not have readily visible aboveground symptoms. often the disease problem remains unnoticed until the peanut is dug. In ARE Peanut areas are widely increased with the increase of land reclamation. Surveying studies were carried out on five peanut cultivars namely Giza 4, Giza 5, local 383, Red race and While race, during season 1994, in two governorates; Giza and Ismailia for percentage of natural occurrence of pod rot diseaes and percentage occurrence of fungi associated with• shells and seeds of different pod rot categories besides the apparently healthy one. Eighteen cvs ,hybrids or lines were evaluated for their reaction to the disease under field conditions during two successive seasons. Effect of some field treatments i.e., fertilization, fungicidal combinations and three growth substances on percentage of pod rot incidence and seed germination of Giza 4 peanut cultivar under field conditions. Isolation frequencies of various fungi on both shells and seeds were recorded with the different categories. Seeds moisture and oil content, acid value, aflatoxins and other mycotoxins were detected. Results obtained could be summarized as follows: I-Pod rot disease was recorded on the five surveyed cvs, in both Giza and Ismailia governorates. 2- The cultivar, Red race was lower than the other cvs. in appearance of disease categories on pods, in the two governorates surveyed. 3- Pods having general breakdown, was the most commonly spread type of pod rot on cvs Giza 4 and Giza 5 with significant difference to the other cvs in Giza and Ismailia. 122 4- The category of pods having dry brown lesions appeared on all cultivated cvs. 5- The lowest percentage of the disease was recorded on Red race and the highest one was on Giza 5. Results also, indicated that the percentage of pink discoloration was low on all cultivated cvs in both governorates. 6-The percentage of pink discoloration was low on all cultivated cvs in both govcrnoratcs. 7-Genera of Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Pythium, Rhizopus, Sclerotium, and Trichoderma, besides Rhioctonia solani, the most common fungi associated with pod rot of peanut, were isolated from peanut pods and kernels, of peanut plants cultivated in the two governorates surveyed. 8-The characteristic fungi of the three disease categories were recorded on the related category. R. solani caused brown rot, F. nunuliformc caused pink discoloration and various other pathogens caused break-down, in the two governorates. 9-hlsariul/I spp. were forms characteristic of discolored shells whereas S. rolfsii was constantly isolated from brown rot and general breakdown, (’lado.\j)oriul/I spp. was constantly isolated from pink discoloration, and Alternaria spp. was constantly isolated from general breakdown, in the two governorates. 10- Genera of Aspergillus, Cladosporium, Penicillium, Pythium, Rhizopus, Sclerotium, and Trichoderma, besides F. moniliforme, F. oxysporum, F. solani; were isolated from both apparently healthy and diseased categories, in the two governorates, Giza and Ismailia. 123 II-Alternaria spp., Fusarium semitectum and Rhizoctonia solani; were isolated only from diseased categories in the two governorates. 12- A. niger, F oxysporum, F. solani, Penicillium spp., S. bataticola and S. rolfsii, were recorded on shell samples of the four categories, in the two governorates. 13- A. flavus. was dominant in all seed samples, especially the apparently healthy one, and was isolated from both shells and seeds samples; of the four categories, in the two governorates. 14- Penicillium spp. followed by A. niger, and Penicillium spp. followed by A. flavus, were the most frequent species isolated from shells and seeds respectively in the two governorates. 15- S. bataticola, S. rolfsii, Penicillium spp. and Trichoderma spp. were isolated from seeds of healthy pods (intact pods), and were dominant in endocarpic community of sound mature peanut fruits. 16- S. rolfsii exhibited the highest percentage of pod rot infection followed by F. oxysporum, on Giza 4 peanut cv in pathogenicity test whereas, F OXYS[JO/’l”” followed by R. solani were more aggressive on Giza 5 peanut cv. but F moniliforme was the lowest one, in this respect. 17- Varietal reaction revealed that pod rot diseases were spread on all cultivars and the eighteen tested cultivars differed greatly ill their reaction to the diseases, in both quality and quantity of pod rot incidence. 18- Under field conditions, addition of K alone, tended to increase percentage of pods having dry brown lesions, and slightly affected incidence of pink discolorations. At contrast, using P gradually reduced pods with dry brown lesions and pink discoloration. Combinations of both; clearly reduced the two categories. 19- The use of N only at the normal level; increased percentage of pods having general breakdown. 124 20- The highest percentage or apparently healthy pods, was recorded with I’K combination or 45-48. 21- Combination of PK at levels 30-48 and 45-48 was the best treatment on seed germination percentage of different pods categories, except for pods having general breakdown. 22- PK fertilization increased Pacelomyces spp. and Penicillium spp. 111 both shells and seeds of all categories, whereas F. semitectum had increased only in seeds of pods having dry brown lesions and Pythium spp. in shells of pods having general breakdown. Besides, A. ochraceus, A. terreus and Trichoderma spp. in both seeds and shells of pods having dry brown lesions, A. flavus in seeds and Rhizopus spp., S. rolfsii and Trichoderma spp. in shells of the same category. 23- Combinations of P and K; decreased A.flavus, A. niger in seeds of apparently healthy pods and shells of pods having dry brown lesions, A. flavus in seeds and shells of pods having pink discoloration, A. niger in seeds of pods having dry brown lesions and pods having general breakdown. 24- Addition of K increased R. solani in only seeds of pods having dry brown lesions. 25- In shells of pods having general breakdown; PK nutnnon increased A. nigel’, whereas A. tennis, A. flavus, Rhizopus spp., ,<{ rolfsii were increased in both seeds and shells of this category. 26- In shells of apparently healthy pods; combinations of PK increased A .flavus, A. niger, S. batatico!a and S. rolfsii. 27- Increasing P level increased average incidence of S. rolf vii in shells and seeds of the four categories except for seeds of dry brown lesions and of apparently healthy pods. 125 28- Increasing K levels increased Pythium spp. but decreased S. hataticola. 29- Moisture content of peanut seeds fluctuated within a wide range as a result of fertilization with the normal level ofN and different levels of P and K. 30- Oil content was greatly high in pods having dry brown lesions at PK level 30-48 and the normal level of N, while the lowest one was recorded on pods having general breakdown at PK level 30-0 and fertilization with N at the normal level. 32-AII tested seed dressing fungicides effectively reduced the incidence of pod rot and consequently increasing percentage of apparently healthy pods. 33-l\llatoxin H. was detected in seeds of pods having pink discoloration and pods with general breakdown which collected from peanut plants treated with Nat normal level and PK at level 30-24. 34-Clear reduction was noticed on the acid value of seeds of apparently healthy pods followed by pods with dry brown lesions as a result of fertilization with the normal level ofN and different levels of P and K. 35- Soil treatment with fungicides had also a good effect in reducing the disease with highly significant differences compared with control. 36- Sumisclex was found to be the most effective one, as both seed dressing and soil treatment, in reducing the disease and recording the highest percentage of healthy pods. 37- Fungicidal application improved germination and generally increased percentage of seed germination38- All fungicides applied; greatly reduced the percentage o,f fungi isolated li’OI11 both shells and seeds of the lour categories, compared with control, with few exceptions, 39- All fungicidal treatments clearly increased seed moisture content than control treatment. 40- Fungicides treatments moderately affected oil content of apparently healthy pods but greatly affected oil content in seeds of pods having general breakdown and pods having dry brown lesions. 41- Fungicidal treatments increased the acid value of peanut oil, compared with control. The lowest acid values were recorded on apparently healthy pods, in most cases with Benlate followed by Sumisclex as seed dressing. 42- All fungicidal treatments inhibited aflatoxins production, with few exceptions on pods having dry brown lesions and pods having general breakdown 43- 1\11 growth substances tested, great ly reduced pod rot of peanut. IBI\ followed by I\TP, at 100 PPM were the best treatments iii increasing percent of apparently healthy pods. 44- In all growth substances treatments, apparently healthy pod was increased, parallel and proportional with increasing concentration. 45- ATP at 50 PPM was the best treatment in reducing pods having dry brown lesions while, 100 PPM had better effect on pods having pink discoloration. 46- IBA followed by ATP, at 100 PPM; were the best treatments in reducing pods having general breakdown. 47- All growth substances treatments clearly increased percentage of seed germination compared with control. ATP and IAA were better than lBA. The highest percentage of seed germination on the four categories was recorded with the concentration of 100 PPM. 48- Growth substances greatly affected occurrence percentage of various fungi associated with both shells and seeds of the different categories compared with control. .ln all treatments, fungi decreased with incrcasing couccntrat ion. 49- Growth substances at concentration of 100 PPM exactly, controlled all fungi associated with both shells and seeds of all categories with few exceptions. 50- Growth substances at concentration of 25 PPM slightly affected percentage occurrence of various fungi on shells and seeds of the four categories. 51- Growth substances at different concentrations, had no consistent trend on peanut seed moisture content of the different categories. The highest percentage of moisture content was recorded on seeds of pods having dry brown lesions whereas the least one was obtained on seeds of pods having pink discoloration. 52- Generally ATP, lAA and lBA at concentration of 25 PPM, reduced oil content, of all categories, with few exceptions. ATP at concentration of 100 PPM raised oil content, of all categories except for seeds from pods having general breakdown. 53- Growth substances at all treatments clearly increased the oil acid value of seeds from both pods having dry brown lesions and healthy pods compared with control. 54- Aflatoxin Bl was detected on seeds of pods having dry brown lesions which collected from peanut plants treated with IAA at 50 PPM. Aflatoxin B1 was detected on seeds of pods having general breakdown previously treated with ATP at 100 ppm and lAA at 50 ppm. The allatoxin type Gl was detected only in seeds of pods having general breakdown previously treated with IAA at 50 ppm. 55- Ochratoxin A was detected III seeds of pods having general breakdown previously treated with ATP at 25 PPM. Ochratoxin A was also detected in seeds of pods having general breakdown where seeds were treated with Topsin-M and cultivated in soil treated with Sumisclex. May be this is the firs! report on the natural occurtancc of ochratoxin A on peanut. |