Post harvest diseases fruits and vegetables - Xavier University ...

More documents

Recommendations

Info

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE Postharvest Disease Summary 313 R, sexualis have never been observed to germinate (Snowdon, 1990). Direct infection can occur if ripe fruits touch the ground or become contaminated by splashing rain (Harris and Dennis, 1980). Infection progresses rapidly, especially in injured fruits. Infections of Mucor and Rhizopus result in a water-soaked appearance. In Mucor, infections in the invaded area rapidly become covered with visible black sporangia containing the asexual spores (sporangiospores). These spores are the inocula for further infection, both in the field and after harvest. Under warm and dry conditions, Rhizopus spp. can initiate a similar infection. At their progressed stage of development, both Mucor and Rhizopus are capable of breaking down the fruit tissue and so causing juice leaks. During storage and marketing further rotting is caused by contact infection between infected and healthy fruits and through contamination with spore-laden juices. At 5°C or below, Rhizopus rots can be controlled. Harris and Dennis (1980) showed that asexual spores of J?, sexualis were inactivated at 0°C and did not recover their viability when the fungus was moved to a higher temperature. Mucor piriformis can, however, infect the fruit and develop even at 0°C. BLUEBERRIES AND GOOSEBERRIES The most important causes of postharvest decay of blueberries are Botrytis cinerea Pers., Alternaria alternata (Fr.) Keissler and, in some instances, Alternaria tenuissima (Kunze:Fr.) Wiltshire, Colletotrichum spp. and Phomopsis vaccinii Shear. In many cases the stem scar is the predominant site of infection for various pathogens of blueberries (Ceponis and Cappellini, 1983; MilhoUand and Daykin, 1983). Mucor piriformis Fischer, the cause for "leak" disease in strawberries and raspberries, has been reported by Dennis and Mountford (1975) as an important pathogen of blueberries as well. Species of Monilinia, which cause the brown rot of stone fruits, are important field pathogens of blueberries (Barta, 1987). Monilinia invades the berries through the flowers, giving rise to diseased fruits that either fall to the ground and turn into ^mummies' or are harvested along with healthy berries. This is why Monilinia species are also included among the postharvest pathogens of blueberries. The major postharvest pathogens of gooseberries are JB. cinerea, M. piriformis and A, alternata. Botrytis invades the fruit in the field via http://arab2000.forumpro.fr
FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE 314 Postharvest Diseases of Fruits and Vegetables the senescent calyx. Infection of the fruit by Mucor frequently occurs following contamination by soil splash after heavy rain (Dennis, 1983a). Infection by Alternaria (and sometimes also by Stemphylium) via the calyx end similarly occurs in the field prior to harvest, and may result in premature fall of infected berries from the bushes. The fungus initially colonizes the seeds. However, when the fruits are stored at ambient temperatures, the fungus can progress and begin to infect the pericarp. Control Measures Chemical control of postharvest diseases of soft fruits has mainly focused on the suppression of B. cinerea, the most important pathogen of these fruits. Since infection originates in the field, fungicidal sprays during the flowering period are the first step in controlling the disease. Preharvest fungicidal application of benzimidazole successfully controlled decay in the early 1970s (Jordan, 1973). Following the emergence of 5. cinerea strains resistant to these chemicals, they have been replaced by fungicides of the dicarboximide group, and preharvest spraying of strawberries with iprodione during the flowering period provided good control of the gray mold disease during storage (Aharoni and Barkai-Golan, 1987). However, these fungicides, similarly to the benzimidazoles, are not effective against Phycomycetes fungi, such as Rhizopus spp. and Mucor spp. (Eckert and Ogawa, 1988), and B, cinerea strains resistant to the dicarboximides have also developed (Hunter et al., 1987). Postharvest fungicidal applications are not practical for ripe berries because of their sensitivity to wetting. A rapid reduction of the temperature from the field level to below 5°C is important for retarding decay development in strawberries during shipment (Harris and Harvey, 1973). This is currently achieved by forced-air cooling, although hydrocooling, which removes field heat from the berries more rapidly than air cooling, cleans them and does not cause moisture loss. The latter has not been recommended because wetting may lead to excessive decay (Mitchell, 1992). In a recent study of the decay hazards associated with hydrocooling, Ferreira et al. (1996) concluded that hydrocooling, with the addition of proper chlorination, has promise as a method for rapid cooling and cleaning of strawberries as well as for reducing the level of S. cinerea inoculum on the fruit surface. These investigators considered that if cooled, good-quality berries were subsequently stored at the low temperatures recommended (0 to 1°C), the risk associated with hydrocooling would be minimal. http://arab2000.forumpro.fr
Page 1 and 2:
FREEDOM PALESTINE FREEDOM PALESTINE
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276: FREEDOM PALESTINE FREEDOM PALESTINE
Page 325: FREEDOM PALESTINE FREEDOM PALESTINE
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395 and 396:
Page 397 and 398:
Page 399 and 400:
Page 401 and 402:
Page 403 and 404:
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419 and 420:
Page 421 and 422:
Page 423 and 424:
Page 425 and 426:
Page 427 and 428:
Page 429 and 430:
Page 431:
show all

Post harvest diseases fruits and vegetables - Xavier University ...

Create successful ePaper yourself

Delete template?

Save as template?