![]() Figure 2: Tomato plant showing defoliation and fruit symptoms due to bacterial spot. Diane Cuppels, Agriculture and Agri-Food Canada. Figure 1: Bacterial spot lesions on tomato leaves. When spots are numerous, foliage turns yellow and eventually dies, leading to defoliation of the lower portion of the plant. Infected leaves may develop a scorched appearance. The lesions tend to concentrate on the leaf edges and tip and may increase in size to a diameter of 3-5 mm. Initial leaf symptoms are small, circular-to-irregular, dark lesions, which may be surrounded by a yellow halo. It is difficult to reliably distinguish bacterial spot from bacterial speck based on visual symptoms, especially in the early stages. The bacterial spot pathogen may produce lesions on all aboveground parts of the plant - leaves, stems, flowers and fruit. Optimum growth temperature ranges for bacterial pathogens of tomato DiseaseĬlavibacter michiganensis subsp. The pathogens multiply much more slowly outside this optimum range. Each pathogen has a particular temperature range, in which it is at its peak rate of growth and infection (see Table 1). Wet conditions in the plant canopy due to rain, fog, dew, high humidity or irrigation give the bacteria a suitable environment for growth. The pathogensīacterial pathogens need moisture to multiply. Seed suppliers, transplant growers, field growers, processors, researchers, extension specialists and crop advisors all have a part to play. Management of tomato bacterial diseases must focus on prevention and must start well before transplanting. Processors also face the risk of falling short of their packing goals. Depending on the product being produced, bacterial disease may result in lower solids, increased costs, slower factory operations and reduced peeled recovery for the processors. Processing growers also face the risk of increased tare penalties and the possibility of not meeting their contracted tonnage. Secondary rots can also develop.īoth fresh-market and processing growers may incur higher sorting costs due to fruit lesions. Defoliation exposes the fruit, resulting in sunscald and poor colour. When present, fruit lesions disfigure and reduce the marketability of both fresh-market and processing fruit (especially in whole-pack or diced product) and interfere with peeling. However, when conditions are optimal for bacterial disease, losses in marketable yield can be up to 60% in some fields.ĭamage from these diseases may range from a light spotting of the foliage to almost complete defoliation of the plant, with corresponding impacts on photosynthesis and production potential. In Ontario, bacterial disease is present at some level every season, though not always at destructive levels. bacterial canker, caused by Clavibacter michiganensis subsp.bacterial speck, caused by Pseudomonas syringae pv.bacterial spot, caused by Xanthomonas campestris pv.Three bacterial diseases are common in Ontario tomato fields: ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |