3-Weed Management for ZT Crops

 Transcript

Today, we look at the third lesson of this week of our CASI course. In this lesson, we will take a look how to control the growth of weeds in our major crops.

First, we understand what weeds are. Weed is a biological hurdle that not only affects crop production but also its quality. Data has shown that we lose around 30 to 35% of production due to weeds. In terms of season, this loss in crop production is around 25% during Rabi season and 35 to 37% during the Kharif season as there is plenty of moisture during Kharif time.

Now, we look at the various techniques to control the growth of weed. The first technique to control the growth of weed is called ploughing technique. Under this technique, we do deep ploughing of our field in order to control weed growth. But this technique cannot come under conservation agriculture as one of the requirements of conservation agriculture is minimum tillage.

The second technique to control weed growth is choosing a crop that is more resistant to the growth of weeds. These crops are usually those whose initial development or growth is very fast and thus it is able to suppress the growth of weed and thereby control the weeds.

Another technique is the solarization of soil. We do this by covering our field with a plastic sheet so that the temperature of the soil increases and this comparatively reduces the growth of weeds. Mulching is another technique to control the growth of weeds. We know that under conservation agriculture, through residue management, we increase the water holding capacity of soil and control the growth of weeds. When there is mulch on the field then it prevents natural resources from getting to the weeds like unideal temperature for weeds and thus suppress their growth.

Now, through manual weeding we can control weed but it also increases our labor cost. This goes against the conservation agriculture principle of sustaining soil while keeping labor cost low. So that is why we give importance to controlling weed through the use of chemicals in conservation agriculture.

There are three types of weeds. The first is narrow leaf weed and these are mainly monocot. The second is wide leaf weed and these include Anagalis. The most common grassy weed is doob and it can be found in every season. In sedges weeds, motha is the most problematic.

Now, we move towards the discussion of rice. Rice is grown using both transplanting rice technique and direct seeding rice technique. In DSR, for weed control, first we apply pre emergence herbicide. Pendimethalin and pyrazosulphoron are commonly used as pre emergence herbicide. You can see on the slide, the various herbicides used and their quantities. Bispyribac sodium is used to control broad leaf weed and narrow leaf weed in both DSR rice and transplanted rice. Under SRFSI project, when we used Bispyribac sodium and pyrazosulphoron as post emergent herbicide to control weed, it increased our productivity and also had the highest weed control efficiency.

So besides Bispyribac sodium and pyrazosulphoron herbicide, we also use Several other herbicides that are shown in the slide to control weeds in rice.

Now, we look at wheat. In rabi crop, the growth of weed is less compared to the kharif crops and thus it is easier to do weed management through chemicals.

In rice, we use Pendimethalin as a pre-emergence herbicide and is used within 72 hours of sowing. It is always suggested the field should be moist before applying pre-emergence herbicide and we always backward spray it.

To control narrow leaf weed, we use Clodinafop or Isoproturon herbicide and for broadleaf weed, the best herbicide to use is 2,4-D Ethyl Ester. We can also use some new herbicides like Sulfosulfuron in place of 2,4-D Ethyl Ester. Sulfosulfuron is an easy to use herbicide and is also used in less quantity. If both monocot and dicot weeds are present in the field, then we can prepare and use a tank mix spray solution of both broadleaf and narrow leaf herbicides.

Now we look at maize which is another important crop. It is mainly grown as a rabi crop. Under SFRSI experiment, the best option we found for weed control in maize was to use Pendimethalin as pre emergence herbicide and use Atrazine and Tembotrione as early post emergence herbicide. So using both Atrazine and Tembotrione, our production and productivity increased and our weed control efficiency improved.

Now, we look at pulses. Most pulses crop are dicot. Now in dicot crop, it is very difficult to control broadleaf weed in post emergence. For pulses, we suggest Pendimethalin for pre-emergence weed control. For post emergence herbicide, we use Quizalofop for narrow leaf weeds and use Imazethapyr for kharif crop. We use 400 to 600 ml in one hectare to control all kinds of weeds. At times, we see some side effects with the use of Imazethapyr as it temporarily stops plant growth for some time.

As far as oilseeds are concerned, we use Pendimethalin as pre-emergence herbicide and we use imazethapyr and imazamox as post emergent herbicide for crops like groundnut and soybean. We use 600 to 800 ml of Imazethapyr and imazamox per hectare for groundnut and soybean.

So using chemical fertilizers not only saves our time but it also saves labor cost and this increases our productivity and maximizes our profit.