Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________________Disease EcologyDeficiency symptoms for major and minor nutrients:• Nitrogen: Light green or yellow older foliage.• Phosphorus: Stunted plants and purplish leaves.• Potassium: Brown leaf margins and leaf curling.• Calcium: Stunted plants, stubby roots. (Causes blossom end rot of tomatoes, tip burn ofcabbage, celery blackheart, and carrot cavity spot).• Magnesium: Yellowing between veins of older leaves.• Sulphur: Yellowing of new leaves, stunted plants.• Boron: Growing points die back and leaves are distorted.• Copper: Yellowing of leaves which become thin and elongated, causes soft onion bulb withthin scales.• Iron: Light green or yellow foliage on youngest leaves.• Zinc: Rust-colored spots on seed leaves of beans, green and yellow striping of corn,yellowing of beet leaves.• Manganese: Mottled yellow area appearing on younger leaves first. In beets, foliagebecomes deeply red.• Molybdenum: Distorted, narrow leaves, some yellowing of older leaves; whiptail leafsymptoms in cauliflower.7.7 Studying diseasesIf despite checking the guiding questions from the section above, it is still unclear if something is adisease, an option would be to observe the symptoms in the field or in a ‘classroom’, or house over aperiod of time. In some TOTs, this is an experiment called disease zoo, disease observatorium ordisease culture. An example for leaf or stem spots is given below.Studying a diseaseSelect one or a few plants in the field that have disease-like symptoms. Mark the plants with a stick andlabel the leaves that show the symptoms (you can put a tag on the leaf or draw a big circle with awaterproof markerpen around the spot you want to study). Draw the plant and the stem or the leaveswith symptoms in detail (use hand lens) using color pencils (what color is the symptom, where is itlocated, do you see structures inside the symptom (e.g. black specks), how does the plant tissue lookaround the symptom, etc.). Measure the size of the symptom and note it down with your drawing.monitoring areasmagnifying glass tomonitor stem spotCome back after a few days and repeat the above: draw and measure the symptoms. If you find that thesymptoms are growing, becoming bigger in size and maybe even have spores (you can sometimes findthem as dusty powder or in small black pustules on the spot) it is very likely that you are looking at adisease. Check the symptoms found with details on some of the major diseases of eggplant (chapter 8)to confirm diagnosis.124Eggplant Ecological Guide