5 Sugarcane diseases and their management
Transcript
Welcome to the last talk of this week. In the last class we talked about the important diseases of groundnut and their management. Today we will be talking about important diseases of sugar cane and their management. Sugarcane is a crop or we can say it’s a cash crop which is affected by a number of disease or pathogens. So most of the important ones include Red rot, Smut, Grassy shoot and Red stripe. These are the four important diseases that are considered to be a more important economically.
Red rot of sugar cane is caused by (Colletotrichum falcatum) and the pathogen survived in infected host debris, volunteer or Ratoon plants. The plant can be easily diagnosed with the disease where the leaf can be seen having a red center and when you split open the canes you can see that the vascular tissues are also red in color. So these are very easy and distinct way of identifying the disease.
So the management of that disease includes IPM practices which are Cultural practices, Use of resistant varieties and Chemical control. And the Cultural practices include uprooting of infected plants if there are only few plants are affected. If there are few plants we can burn them as well so that the inoculum is destroyed. The crop rotation is very important in this management of this particular disease where we should go for at least three years of crop rotation with a non host. Similarly use of digits free sets for planting is also very important because pathogen is harbors in the infected host debris. Then hot water treatment of the sets before planting at the temperature of 52o C for 30 minutes is one of the most effective control measure for management of the particular pathogen. Dip fresh setts at 0.25% solution of Agallol and Aretan is also recommended. Resistant varieties wherever available we should grow those resistant varieties for having a disease-free crop. Other chemicals that includes Sett treatment with 0.2% Thiophanate methyl, Benomyl and this both can protect the plant up to 90 days. So these are some of the effective control measures that are recommended for management of the Red rot pathogen of sugar cane and again we could see that cultural management of this particular pathogen is more important than management with chemicals and other sources.
The next pathogen is Ustilago scitaminea. It causes smart disease in sugarcane. The disease is often manifested by the smutted or whip-like appearance of the top tissues. The stem becomes whip-like and it is fully covered by Smut spores. The Smut spore can also be seen by opening the unfolded leaves of the stem. The pathogens survive in infected hosts. So management practices include Cultural, Use of resistant varieties and Chemical methods.
Cultural methods include removing of the whip with thick cloth without allowing the spore to shed and destroy. So once we take out the whip it should be covered with a cloth so that the smut spores are not distributed or does not fall on the other healthy plants so, this care should be taken. The use of disease free sets are also recommended for planting. Treat the sets with hot water it is again advisable that is at 52oC for 30 minutes and we should not take Ratoon crops for the infected areas because the ratoon crops may harbor the pathogen and it may pass on the pathogen to the fresh crop. Resistant varieties are reported in many areas so resistant cultivars should be used for management of this pathogen. Chemical include Carbendazim which is the one of the best chemical for management of this particular pathogen.
Next is Grassy shoot of sugarcane and it is caused by virus. The pathogen is in survived in the infected host. The disease is very easy to diagnose where the sugarcane set does not develop into normal shoots rather there it’s grass like appearance, the shoots become grass like in nature. So it is the only the cultural practices that are helpful or removing the particular disease. This includes uproot and destruction of the affected clumps because in this way we avoid spreading of the virus from the infected plants to the healthy ones. We should also avoid taking sugar cane crop for next 3-4 years so crop rotation with a non host for 3 to 4 years has proved very effective in management of this particular virus. Fresh sowing is done after three to four years with seed sets from resistant variety. Some resistant varieties are reported. So after three to four years of crop rotation one should go for utilization of resistant varieties for taking a fresh crop. Sett treatments with hot air at 54o C for eight hours to inactivate the causal agent virus is again recommended as it is another easy way of managing the disease. Use of disease-free sets for planting is again important hot water treatment is also effective where we should treat the sets at 50o C for at least two hours and control of aphids by spraying suitable insecticides is also recommended because the virus is aphids transmitted so we can avoid spreading of this virus through effective management of aphids.
The next disease is Red stripe and it is caused by a bacterium that is Xanthomonas albilineans. So red stripe is easy to diagnose because here in the leaf instead of a single red middle portion here you can see that different stripes are developed on the leaf. The pathogens survived epiphytes on sugarcane phyllosphere. So this is the main mode of survival of the pathogen. So IPM practices includes mostly the cultural practices as there is no recommended chemicals that are available for management of this particular bacterium. When the affected plants are few in numbers then we can easily take out these affected plants and we can destroy them or even burn them. But if the whole field is affected then we should discard the field for at least three to four years for sugarcane cultivation. Fresh sowings should be done with resistant varieties wherever the source is available and it helps in reducing the disease severity. This is a difficult disease of sugarcane to control so therefore whenever disease is noticed the affected plants should be removed and burnt immediately. Otherwise, once the pathogen is established in the field it is very hard to remove from the field and that is why its establishment should be avoided. Systematic destruction of affected plants reduces the disease incidence and growing resistant varieties are the best management practices for managing this particular disease. So these are the important sugarcane diseases and they cause severe loss to the sugarcane crop every year. So we should go for adequate cultural and resistance sources for management of these diseases wherever it is applicable and thereby we can save the losses that farmers are occurring every year. With this we have come to an end of all the five topics of this particular week. In the next week we’ll be talking about diseases of vegetables and other cruciferous plants.
Thank you.
