How to Detect Pathogens in Citrus Fruits
- 1). Look up the pathogens you might find in your fruit. Reference materials published by the Food and Drug Administration (FDA) or the U.S. Department of Agriculture (USDA) provide useful information on the species and strain of pathogen that infest a citrus fruit. Learn the specific fruit disease to look for. Three diseases that have been found in the U. S. are black rot named Alternaria citri., citrus canker called Xanthomonas axonopodis pv. citri and rotaviruses. Write down the list of symptoms and a short description of how the disease damages the stems, leaves and fruit.
- 2). Know the area where the fruit is grown. Diseases develop in specific growing areas. Take the time to read current reports on diseases found in your fruit's growing area. Local fruit experts or national agencies like the FDA and USDA publish reports.
- 3). Inspect the tree leaves, stems and fruit at a citrus fruit farm or on a tree in your yard before the harvest. First, look for a healthy, mature fruit. You can see weaker body and skin in a diseased fruit that has not developed properly. Fruit might be small, irregularly shaped, mushy or weak to the touch. Look on the ground to find if diseased fruit have fallen off the tree. Look at the surface to find blemishes from decay, steeping or abnormal growth.
- 4). Inspect the fruit when you pick it. By this time, you can check to see that fruit has fully matured. Note the smaller and poorly shaped fruit. Look for discolored areas and developed rot, spots or cankers. Using your reference description, check the symptoms to know the specific disease. Examine suspicious fruit more carefully with a magnifying glass.
- 5). Examine produce to find damage from pre-harvest pathogens and pathogens that infect the produce in transport or storage. Bacteria, viruses and fungus infect fruit during transport and storage. At a store, look over a fruit carefully, paying attention to the discolored areas and blemishes. Lightly touch around the fruit surface to find decayed parts inside the fruit.
- 6). Take a sample and examine under a microscope if you prefer a scientific method. The test reveals more than you can see or feel. For example, test for black rot by taking a spore sample from an area inside the fruit that turned black and steeped during storage. You can detect a green fluorescence under the microscope.