Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of EggplantRelated exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:3-D.1. Pot experiment to test whether root diseases are soil-borne3-D.2. Use of subsoil to manage root disorders in the nursery3-D.3. Steam sterilization of soil for the nursery3-D.4. Soil solarization to manage root diseases in the nursery3-D.5. Test effect of soil solarization in the field8.1.3 Rootknot nematode - Meloidogyne sp.See photo 17 (page 177).Species belonging to the rootknot nematode family include Meloidogyne incognita, Meloidogyne javanicaand Meloidogyne arenaria. They are all very small worm-like creatures living in the soil and feeding onplant roots. The rootknot nematodes have a very wide host range including most of the commonly grownvegetables and many common weeds.Signs and symptomsPlants affected by nematodes may wilt during warm weather, or in the middle of the day, but recoverafterwards. The rootknot nematode sucks on the roots of many plant species. This feeding activitycauses enlargement of the roots and the production of the root galls. Root galls are a typical symptom ofrootknot nematode infection. A large number of (female) nematodes can be present inside a gall. Onefemale can lay up to 600 eggs. The egg masses (or egg sacs) are usually placed outside the gall. Theegg sacs can be seen with the bare eye as yellow-whitish round sacs, but it takes some experience tonote them. The nematodes live in the upper 60 cm of the soil.Source and spreadNematodes are small worms that can travel small distances through the soil. The most important methodof spread, however, is in soil attached to feet of field workers/visitors and animals, tools and implements,etc. Soil particles spread by wind or in ground or irrigation water is another way of spreading thenematode. Nematodes can also be transported in soil which is carried on the roots of transplants.Role of environmental factorsA soil temperature of 26-28 o C is highly favorable for the development of rootknot nematode, particularlyon light, sandy soils. High temperatures of 40-50 o C kill the nematodes. In infested nursery fields, it maybe worth trying solarization or other soil sterilization methods mentioned in section 3.10.1.Rootknot nematodes: how to see them!It is important to recognize the symptoms of rootknot nematodes, especially the early symptoms.There may still be time to take some action to prevent population build-up and severe cropdamage. Root galls are typical symptoms of rootknot nematodes. At an early stage however, or incase of a single gall only, it can be difficult to identify if the symptoms are actually caused byrootknot nematodes. This test can be done to help early identification and to confirm diagnosis. Itis also a way to actually see the nematodes.rootknot nematodes: males femalesIt should be noted that it takes some experience to recognize the nematodes (needs experiencedfacilitator). Also not all galls contain living nematodes, so some trial and error may be necessary.Collect fresh root galls from the field, wash the roots with water to remove soil particles. Put asmall layer of clean water on a dark-colored plate. Place the root gall in the water, and crush itthoroughly using pocket knives or needles. Nematodes will be released from the gall and float tothe water surface. Female nematodes can be seen as very small, whitish colored, round to pearshapedstructures. Males are smaller and cannot usually be seen with the eyes. Males are notround but long (worm-like) in shape.135Eggplant Ecological Guide