Viruses can cause a wide range of symptoms , unusual petal color streaking can be one .
“
Some symptoms may be immediate and striking while others may be quite subtle and require a great deal of experience to recognize the early signs .”
Aphids and other insect pests such as thrips and whitefly are major vectors of crop viruses .
Color disorders are common signs of some viruses .
TYPES OF VIRUS DISEASES AND SYMPTOMS
While there is a large number of viruses that may infect greenhouse crops , the most widely occurring in hydroponic crops and greenhouses are tomato mosaic , cucumber mosaic , tobacco mosaic , lettuce mosaic , tomato spotted wilt virus , double streak virus , tobacco etch , curly top , tomato yellow leaf curl , and pepino mosaic . Each virus is often not specific to one species of plant — tobacco mosaic and tomato spotted wilt virus can each infect many species including many weeds , vegetable , ornamentals , and flowering plants — they are not just limited to tobacco and tomato . The name of these types of viruses only indicates the crop it was first identified in , not the species it can infect . Viruses may produce a range of symptoms from barely distinguishable to severely deforming and may including leaf mottling , chlorosis , and other color disorders , twisting , curling , and deformities such as shoestring-like growth , stunting of growth , dwarfism , fruit disorders , death of the growing point , and numerous deformities or color disorders of flowers , foliage , and fruit . Some symptoms may be immediate and striking while others may be quite subtle and require a great deal of experience to recognize the early signs . Virus damage can range from a few mildly infected plants to serious plant and yield losses . Often the main issue with a virus outbreak is a lack of correct identification and many mild virus symptoms are often mistaken for other diseases , nutrient deficiency or toxicity , or physiological disorders . One good indication that a virus may be present is if one or only a few random plants start to show unusual symptoms . Issues caused by nutrient disorders , spray / chemical damage , or the growing environment typically display on many plants or larger groups of plants at the same time , virus outbreaks typically start on one or a few plants and gradually spread more widely . To complicate matters further , virus-infected plants may not show a great deal of outward symptoms — some may have slightly stunted growth or low yields , others may only develop diagnostic symptoms under certain conditions or as plants reach a certain stage of growth and development . While the development of characteristic symptoms is the main method of diagnosis of common viruses , there have been some test kits developed for use in certain crops . Most of these , however , only test for one specific virus , so may not be that useful if a different virus is present .
VIRUS PREVENTION
Many modern hybrids of crops such as tomatoes , capsicum , and cucumbers have inbred resistance to a range of common viruses , and this is the most effective form of prevention from virus infection . Use of commercial , high-quality seed supplied by a reputable company is also recommended for virus prevention as some viruses can be seed borne and easily transferred to a new crop during propagation . Crops should be regularly scouted for signs of unusual growth such as leaf twisting or crinkling , mosaic , or other strange color disorders or stunting and culled rapidly to prevent further spread . Infected plants should not be composted , and plant debris can still act as a source of infection via insect pests and some viruses can be carried within organic mater such as composts and mulches . Bagging up and disposing of virus-infected plants , away from the growing area , is the safest option .
30 Maximum Yield