**10. Conclusion and policy implication**

From the above discussion of the chapter, it is confirmed that weeds are the major challenge in CA crop production systems, where almost 16 to 42% yield reduction is occurred due to weed infestation and one-third of the total cost of cultivation is spent on weeding. On an average of 13.1% of crop reproduced is actually lost in the farmers' fields even after adopting in traditional weed control. The zero/strip-tilled/permanent beds or till the soil with fresh beds based crops production system is an alternate option through mechanized precision planting within a single pass. Although, the CA-based crop management techniques will be faced the major concern of weed management initially. Therefore, proper weed management

*Maize - Production and Use*

fluorfen 0.150 kg ha<sup>−</sup><sup>1</sup>

glyphosate (5.25 kg ha<sup>−</sup><sup>1</sup>

mixture of pre-emergence.

cob<sup>−</sup><sup>1</sup>

(6.7 kg ha<sup>−</sup><sup>1</sup>

pre-emergence atrazine at 1.0 kg ha<sup>−</sup><sup>1</sup>

reported that when atrazine 1.25 kg ha<sup>−</sup><sup>1</sup>

) and atrazine 1.25 kg ha<sup>−</sup><sup>1</sup>

) with maximum net returns.

delay weed resistance against specific weeds.

Recently, a study conducted in a clay loam and sandy loam soils of Bangladesh as a weed management strategy in pre-emergence and post emergence combinations and results showed that the even application of both Pendimethalin and atrazine separately reduces the weed biomass, weed population at 30 days after seeding which further provided better crop yield [58]. In another study clay soils of Rajendranagar (Telangana, India) was found that the highest crop dry matter was recorded with two times HW (at 20 and 40 DAS), which was at par with

pre-emergence followed (fb) protected spray of non-selective herbicide (Atrazine

3 WAS) produced the significantly higher yield than weedy check [60]. An experiment was conducted with application of atrazine or glyphosate herbicide alone and tank mix application of selective (atrazine) and non-selective (glyphosate) herbicides and found that the grain yield was 170 and 70% more when atrazine +

application of atrazine or glyphosate, respectively [26]. Similar to previous study, a field research in the sandy clay loam soils of Kampasagar (Telangana, India)

as a pre-emergence in tank mixture produced the significantly maximum grains

yields were recorded when applied atrazine alone as pre-emergence 1.25 kg ha<sup>−</sup><sup>1</sup>

Application of herbicides after the emergence of maize and weed are wellknown as post-emergence herbicides. Generally, post-emergence herbicides spray/ apply in standing crop targeting weeds canopy by using the sprayer equipment.

when applied as a post-emergence for effectively control of weeds in CA-based maize system are Atrazine, Tembotrione (Laudis), Halosulfuron methyl (Sempra), Tembotrione (Laudis) + Atrazine, Halosulfuron methyl (Sempra) + Atrazine [58]. Earlier findings [62] revealed that pre-emergence herbicides pendimethalin and atrazine reduced the grassy and broadleaves weed population to a significant extent and among the pre-emergence herbicides, later (atrazine) resulted in a higher reduction in grass weed population at the early stage (20 days after seeding) than former (pendimethalin). But further he suggested, the post-emergence herbicides, the mixture of tembotrione + atrazine was more effective in controlling all classes of weed flora at 40 and 60 DAS. Tembotrione alone also showed good control of grasses and broad-leaved weeds. Atrazine as pre-emergence followed by (fb) tembotrione + atrazine as post-emergence found best combination and this combination reduced the weed dry matter to the tune of 98.7 and 97.9% at 40 and 60 DAS, respectively which ultimately resulted in significantly higher grain yields

However, when a single herbicide is used for a long time for controlling the same weeds it may create resistance against the specific weed(s). Therefore, long term basis continuous use of the same herbicide should be avoided. So, it should be rotated with the use of multiple herbicides with a different mode of action to avoid/

The most popular/well-known herbicides which have been found to be effective

**8. Effect of post-emergence herbicides on weed control in maize**

, cob diameter and 100 grain weight than other herbicides [61]. Similar grain

(WAS) or Pendimethalin as pre-emergence at 1.5 kg ha<sup>−</sup><sup>1</sup> *fb* Paraquat 0.6 kg ha<sup>−</sup><sup>1</sup>

+ paraquat 0.60 kg ha<sup>−</sup><sup>1</sup>

as pre-emergence at 1.25 kg ha<sup>−</sup><sup>1</sup> *fb* Paraquat 0.6 kg ha<sup>−</sup><sup>1</sup>

+ paraquat 0.60 kg ha<sup>−</sup><sup>1</sup>

) were applied as tank mixture than weedy check and sole

+ paraquat 0.75 kg ha<sup>−</sup><sup>1</sup>

+ glyphosate 0.5 kg ha<sup>−</sup><sup>1</sup>

, followed by oxy-

were applied

(7.0 kg ha<sup>−</sup><sup>1</sup>

at

) as tank

at 3 weeks after sowing

[59]. The sequential application of

**122**

(11.57 t ha<sup>−</sup><sup>1</sup>

is considered one of the most important prerequisites in CA-based crop cultivation systems including maize to ensure high crop yield. High weed pressure in association with maize, increase to lower the economic returns and, in extreme cases complete failure of the crop. Hence, judicious weed management in CA system is a critical factor for securing and sustaining food security. While, number of repetitive tillage operations increase the cost of cultivation, fuel consumption and delays planting in two ways by repetitive tillage operations followed by manual sowing. After post seeding of maize, farmers are facing major challenges for weed management due to lack of pre-sowing, pre- and post-emergence herbicides.

Since the traditional weed management in maize systems after 30–35 days after seeding; generally, farmers cut the weeds with hand weeding which further consumed more labour or sometimes usually reluctant to control weed in the maize field. However, sometimes they weeded by hand, which proves uneconomical due to be increasing labour wages as well as lack of labours due to migrating from the villages to urban areas for better livelihood. The hand labour based weeding in many developing countries consumes up to half of the total labour demand. Therefore, CA-based new agronomic management practices may be advocated to overcome the above challenges. To address the weed management problems in CA-based maize production under no-till systems with different chemical weed control is a potential means for controlling weeds and more economical compared to hand weeding. Now some herbicides are available in the market for controlling weeds since these should be needed to validate for controlling weeds as well as to know their residual effect on the environment.
