What Is Rice Sheath Blight: Treating Sheath Blight Of Rice
By: Teo Spengler
Anyone growingrice needs to learn the basics about diseases that affect thisgrain. Whatis rice sheath blight? What causes rice sheath blight? Read on to get answersto your questions about diagnosing and treating rice with sheath blight.
What is Rice Sheath Blight?
When your rice crop looks diseased, the odds are good thatyou have rice with the fungal disease called rice sheath blight. What is ricesheath blight? It is the most destructive disease of rice in many states.
This blight doesn’t only affect rice. Other crops can behosts of this sheath blight as well. These include soybean, bean, sorghum,corn, sugarcane, turfgrass and certain grass weeds. The destructive pathogen isRhizoctonia solani.
What are the Symptoms of Rice with Sheath Blight?
The early symptoms of sheath blight include oval circles onleaves just above the water line. They are usually pale, beige to pale green,with a darker border. Look for these lesions at the junction of the rice plantleaf and the sheath. The lesions can joint together as the disease progresses,moving up the plant.
What Causes Rice Sheath Blight?
As previously mentioned, the disease is caused by a fungus, Rhizoctonia solani. The fungus issoilborne and overwinters year to year in the soil taking the form of a hard,weather-resistant structure called a sclerotium. A sclerotium floats on riceflood water and the fungus infects other rice plant sheaths it contacts.
Damage from rice sheath blight varies. It ranges fromminimal leaf infection to grain infection to plant death. Both the amount ofgrain and its quality are reduced as the blight infection prevents water andnutrients from moving to the grain.
How Do You Treat Rice with Sheath Blight?
Fortunately, treating sheath blight of rice is possibleusing an integrated pest management approach. The first step in rice sheathblight control is to select resistant varieties of rice.
In addition, you should use sound cultural practices interms of spacing rice plants (15 to 20 plants/per square foot) and plantingtimes. Early planting and excess nitrogen applications are to be avoided.Foliar fungicide applications also work well as rice sheath blight control.
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Expression of antimicrobial peptide snakin-1 confers effective protection in rice against sheath blight pathogen, Rhizoctonia solani
Rice sheath blight disease caused by the necrotrophic fungus Rhizoctonia solani, is an economically detrimental fungal disease which significantly affects rice productivity worldwide. Potato snakin-1, a cysteine-rich basic antimicrobial peptide (AMP), is a member of the novel Snakin AMP family. In order to assess the ability of the snakin-1 peptide in protecting rice against the sheath blight disease, we have developed transgenic rice constitutively expressing the snakin-1 peptide. The antimicrobial activity of snakin-1 was evaluated against the sheath blight pathogen Rhizoctonia solani both in vitro and in planta. Crude protein from transgenic rice leaves showed in vitro antifungal activity against Rhizoctonia solani. Moreover, in planta bioassay results also confirmed the same, wherein snakin-1 expressing rice plants showed significantly enhanced protection against the sheath blight disease. This report demonstrates how a member of the Snakin family of antimicrobial peptides has been successfully used to generate sheath blight resistance in rice, without compromising on its agronomic characteristics and at no phenotypic cost.
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Inhibition of OsSWEET11 function in mesophyll cells improves resistance of rice to sheath blight disease
- 1 College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China.
- 2 College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China.
- 3 Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
- 4 College of Resources & Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
- 5 Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
- 6 Department of Agricultural and Biological Technology, Wenzhou Agricultural Science Research Institute (Wenzhou Vocational College of Science & Technology), Wenzhou 325006, China.
Application of nano‐materials has widely influenced drug delivery, cancer therapy [ 1 ], energy [ 2 ], biomedical [ 3 ], agriculture [ 4 ] and many other high‐tech industries over recent years [ 5 ]. Nanotechnology has led to the new ways to control diseases using atomic‐scale materials [ 6 , 7 ]. The extremely small‐scale particles have emerged as modern agents owing to their large surface to volume ratio which provides a large contact surface with pathogen sources [ 8 ]. Nanotechnology can have a great impact on natural processes and agriculture by introducing small scale tools [ 9 ] plant protection products [ 10 ] fertilizers [ 11 ] water purification and pollutant remediation [ 12 ] nanosensors, diagnostic devices [ 13 ] and plant genetic modification [ 14 ].
Among nanoparticles (NPs), silver NPs (SNPs) can attack microorganisms, including the cell membrane structure in large‐scale biological processes [ 15 , 16 ]. The antibacterial activity of silver ions has been well established and attributed to the ability of ionised SNPs to penetrate into the bacterial cell wall and to modulate cellular signalling [ 17 ]. SNPs with fungistatic, bacteriostatic and plasmonic properties are among the eco‐friendly inhibitors against plant‐pathogens compared with synthetic fungicides [ 18 ] however the antifungal ability of SNPs has received less attention compared with medical and pharmaceutical sciences with only few studies undertaken against phytopathogenic fungi such as Alternaria alternata, Botrytis cinerea [ 19 ] and Colletotrichum gloeosporioides [ 20 ].
Rice (Oryza sativa L.) is a major food for a large proportion of the world's population, and is an important primary crop in muddy farmlands [ 21 ]. Sheath blight disease caused by Rhizoctonia solani Kühn AG1 (Teleomorph: Thanatephorus cucumeris anastomosis group 1 IA, AG1 IA), is a common destructive disease of rice in all rice‐growing regions in the world. Sclerotia germination is a key factor in the dispersion of rice sheath blight disease, hence any potential inhibitor of sclerotia germination, i.e. SNPs, would be essential in order to decrease the inoculum. This impels rice farmers to use a large amount of anti‐nature and harmful chemicals annually to control sheath blight disease, which not only adds further costs in the short term but increases devastative damages in the long term to the human health and environment.
In this study, in order to control rice sheath blight disease with emphasis on the cleaner production at a lower cost, different concentrations of SNPs were examined as a new antifungal substance to suppress the pathogenic activity of R. solani under in vitro (to evaluate the inhibitory effects of SNPs on sclerotia formation and mycelia growth) and in vivo (to investigate the effects of antifungal activity of SNPs on the rice plant in a glasshouse trial) conditions.
Sheath Blight it is an important disease because it disrupts the regular plant growth. It impacts flag leaf reducing the photosynthesis capacity of the plant and causing severe damage. Besides yield reduction, infected flag leaf also causes stress that leads to poor pollination.
Sheath Blight can lead to severe losses in rice productivity and grain quality by destroying rice sheath and leaves, with yield reduction by up to 50%.