Plant Disease Management - 3

As I read about the subject, I find some interesting insights. But the key theme stays, you need to understand the crop you are planting. Every crop behaves differently and if you do not know the behaviour pattern, you will not be able to handle the crop correctly.

Plant Spacing

Tomato Leaf Curl

In some plants diseases spread if the spacing is close, while in others, open spacing helps the spread of disease. Potato and grapes are two crops that are examples of situations where close spacing promotes the spread of disease.

On the other hand, there are situations where dense sowing helps reduce the spread of diseases. Examples are tomato - where the white fly is responsible for transmitting the leaf curl virus. Similar cases can be seen in cucumber, groundnuts, soybean and in cotton as well.

Possibly, and I emphasize, possibly, where the disease is spread by insects, close planting may help arrest the flight and improve resistance to disease. One needs to study the crop and plant accordingly.

Nutrient Management

Even nutrient management has an impact on disease control. The key nutrients one can control are nitrogen, phosphorus and potassium. Here are some instances -

Cereal Rust

• Fields where potassium is applied appear to be less affected by cereal rusts
• Lack of calcium aids the spread of wilt disease in tomato
• Lack of zinc causes faster spread of downy mildew in maize

Once again the lesson is clear. Once you decide the crop, read up about its individual characteristics. 

I have just started my own farm in Chitrakoot District of Uttar Pradesh India. While it will take time to shine and glow, I intend to take it forward one step at a time. You can visit my farm site here. Any comments welcome.

Plant Disease Management - 2

This section takes off from my previous post where I discussed some generic issues related to plant disease management. I had ended that post with a section on Cultural Methods where farmers could take take advance, proactive methods to prevent disease from occurring in the first place.

picture courtesy http://www.freenaturepictures.com/ 

1.      The first of these methods was the selection of disease free sowing material. This should have been obvious, but it seems that many farmers do not really devote adequate attention to this critical aspect. This involves different issues.

• Drying and storage - seeds with moisture are more prone to fungus. If they are infected with a pathogen, moisture helps it stay alive. Thoroughly dried seeds have far fewer possibilities of carrying viable germs. Researchers have found that prolonged storage of seeds for long periods also helps in killing off the pathogen in them. One can experiment with seeds of different ages to find the best option. In many cases, two year old seeds have been found to give better results than seeds from the previous season. But, like I said, experiment to see what works best for you. 
• Cleaning - Careful cleaning will prevent many problems. Remove the dust and dirt from seeds and soak in a 5% salt solution. Remove any floating impurities and dry the seed thoroughly. 
• Harvesting time can be critical - some plants (and seeds) become more vulnerable to disease if they are harvested too early or too late. For many tuberous plants, removing the green tops and letting the tuber stay in the soil for up to 15 days reduces the possibility of disease. 
• Heat treatment of seeds - this is a complex issue and each type of seed and pathogen seems to have its own preset temperature and the duration for which it has to be heated. You can see some of the complexities involved if you read the abstract of a scholarly article on the subject. 

2.      The second method is about minimizing plant disease. Farmers can do a lot to ensure that their farm starts with a better possibility of a good crop. 

• Crop rotation - planting the same crop over and over again allows the pathogen to grow in the soil. Regular crop rotation helps starve the pathogen of its nutrient base and keeps them in check. Crop rotation also has the effect of improving nutrient availability in the soil, leading to a healthier crop with a better chance of avoiding disease. For example, the Arhar plant is susceptible to a wilt causing fungus. This lives in the root of the plant and can survive for up to a year in the soil. Skipping a year before planting Arhar again helps kill the fungus. 
• Fallowing - the field can be left without planting for a season. Fallowing can be dry, wet or flooded. In wet fallowing we create conditions for the pathogen to germinate but it dies because there is no host plant to support it. In flood fallowing, the aim is to kill the pathogen by depriving it of oxygen. 
• Mixed cropping - reduces plant disease by stopping the spread of plant disease and breaking up the area within which the disease can spread. If the two crops are selected correctly, then one crop can actually inhibit the spread of disease to the other. If Arhar and Sorghum are planted together, Hydrogen Cyanide emitted from Sorghum roots kills the fungus that causes Arhar to wilt. 
• Sowing time adjustment - in some cases, a farmer can plant seeds slightly early (or late) to take advantage of different rates of growth of the plant and its pathogen. In some cases it is possible to plant early so that the plant is at a stage of greater maturity before the conditions become favorable for the spread of the disease. Once again this is a question of knowledge and experimentation and looking for information online and in publications. 

Plant Disease Management - Part 1

What follows is a short discussion on plant disease management in farms. I have used data from varying sources. An excellent resource for the subject can be found here. Here are some key points.

Some typical plant diseases in rice - courtesy e-KrishiShiksha  

Plant disease management takes planning - you can minimize the damage and the effort required to control disease if some early planning is done before you plant your seeds or prepare a nursery. If a farmer makes an attempt to study the crop that is being planted he will be able to create a proactive plan that will handle several kinds of diseases simultaneously. Farmers need to know the causes, mode of spreading and control over diseases to be able to devise a good plan. Some key issues to understand are -

• The source of disease
• The mode by which the disease impacts the plant
• The mode of transmission
• The effect of the environment

Stopping spread of disease - once the disease takes hold, further spread can only be stopped if the propagation cycle of the disease is broken. Once again, this implies detailed knowledge of the disease cycle and the manner of its spreading.

Individual farm initiatives may not work - it is a sad fact of farm life that you can not isolate your field from your neighbors. Water will flow across, dust will fly, germs will spread and insects will cross over all the time. Therefore, it must be accepted that any effort you put in would seldom yield optimal results. However, an innovative farmer can adopt a number of solutions that may make sense. You could rotate your crops, plant a different crop from what is being planted in the neighborhood and stagger your planting so that your crop is at a different stage of growth as compared to others.

Cultural methods  -  if enough information is available, farmers can take proactive steps to minimize the spread of disease. (My take is that we must take these steps even if complete information is not available). These consist of three main steps -

• Select disease free sowing material
• Implement practices that minimize possibility of disease
• Field sanitation and preperation

I have just started my own farm in Chitrakoot District of Uttar Pradesh India. While it will take time to shine and glow, I intend to take it forward one step at a time. You can visit my farm site here. Any comments welcome.

Drip Irrigation in India

If farming has to be viable, farmers have to innovate and accept new technology. If a farmer can afford a motorcycle (and some clearly can) then he can also afford a drip kit. One need not go whole hog to cover the entire field all at one go. Incremental growth is possible and indeed makes more sense. 

This link will take you to an interesting article in Forbes India that talks of a simple drip solution implemented in Jharkhand. Hundreds of similar solutions are possible. Complete drip kits are available on Amazon.in (and possibly on many other e-commerce sites).

If you are managing a small vegetable garden, you can probably get by without any fancy equipment and still get the benefit of drip irrigation. Home made equipment with simple taps to control the flow can work too. The intention is to save water by applying it at the root of individual plants, avoiding deep percolation, keeping surrounding soil dry and minimizing labor. 

The problem also lies in farmer education. How many of our farmers can access YouTube to see how a drip kit is installed or its location changed? 

Many things need to change. They will not happen all at once. I think the solution lies in putting one foot ahead of another and in moving forward all the time. 

I have just started my own farm in Chitrakoot District of Uttar Pradesh India. While it will take time to shine and glow, I intend to take it forward one step at a time. You can visit my farm site here. Any comments welcome.