Protection technologies for mixed crops of maize and sunflower against weeds

Why intercrop maize with sunflower and how to protect seedlings

Mixed cropping of maize with high-protein crops helps solve the problem of protein deficiency in feed and improve the overall efficiency of forage production. Suitable crops for intercropping with silage maize include soybean, lupine, field bean, and sunflower. Co-cultivation of maize with sunflower provides the maximum yield of high-quality feed per unit area with minimal labor and financial costs.

• Sunflower seeding rate in the mixture — 200 thousand seeds/ha
• Dry matter yield per hectare — 14.66 t
• Energy value per hectare — 11980 feed units
• Crude protein harvest per hectare — 1.36 t

Due to wide-row sowing, maize competes poorly with weeds, which leads to a loss of 85–90% of the green mass harvest. Clean soil is vital for sunflower both during seedling emergence and during the second growing season period when generative organs are formed. Pre-emergence application of soil herbicides helps protect both crops during the first thirty days of development.

The classic technology for protecting sunflower crops from weeds is based on the use of the following preparations:

• Gardo Gold, SC;
• Dual Gold, EC;
• Racer, EC;
• Extracorn, SE;
• Estamp, EC;
• Camelot, SE;
• Acris, SE.

Trial conditions and treatment schemes

The preparations were tested in field trials on sod-podzolic light-loamy soil with a randomized block design. The crops were sown in the first ten days of May according to standard agricultural practices. The seeding rate for maize was 90 thousand viable grains/ha, and for sunflower — 50 thousand viable seeds/ha. Herbicides were applied using a broadcast method with a "Euro Pulve" knapsack sprayer and a tractor sprayer with a working solution application rate of 200 l/ha.

Small-plot trials were set up with four-fold replication with a plot area of 20 m², and production trials — with two-fold replication on an area of 1 ha. During the growing season, phenological observations of plant growth and development were conducted. The harvest was recorded per plot, after which the obtained data were processed using variance analysis.

Weed infestation was assessed one month after herbicide application. Accounting plots measuring 0.5×0.5 m (0.25 m² each) were marked on the plots. For quantitative and weight-based accounting of weeds, 2 plots were used in small-plot trials and 10 plots — in production ones.

In the small-plot trials, the biological efficacy of the following herbicides was evaluated:

• Gesagard, SC (prometryn, 500 g/l);
• Extracorn, SE (S-metolachlor, 312.5 g/l + terbuthylazine, 187.5 g/l);
• Herbisan, SE (S-metolachlor, 375 g/l + terbuthylazine, 125 g/l + mesotrione, 37.5 g/l);
• Adengo, SC (thiencarbazone-methyl, 90 g/l + isoxaflutole, 225 g/l + cyprosulfamide /antidote/, 150 g/l);
• Egida, SC (mesotrione, 480 g/l);
• Brig, SC (prometryn, 500 g/l);
• Racer, EC (fluorochloridone, 250 g/l);
• Pronit, EC (propisochlor, 720 g/l);
• Dual Gold, EC (S-metolachlor, 960 g/l);
• Estamp, EC (pendimethalin, 330 g/l);
• Frontier Optima, EC (dimethenamid-P, 720 g/l).

In production trials, the following were used to protect mixed crops:

• Extracorn, SE;
• Stomp Professional, CS;
• Tank mixture of Dual Gold, SC + Stomp Professional, CS.

In mixed maize-sunflower crops, the efficacy of pre-emergence herbicide and tank mixture application was 77.5–99.4% by number and 81.3–99.7% by mass. Pre-emergence application of the herbicides Extracorn, SE and Estamp, EC, as well as tank mixtures of Frontier Optima, EC + Brig, SC and Dual Gold, EC + Estamp, EC, showed high biological efficacy and selectivity towards maize and sunflower (these variants were selected for testing under production conditions). The biological efficacy of the Extracorn, SE herbicide was 95.8% by number and 91.1% by mass; Estamp, EC — 99.4 and 99.7%; the tank mixture of Frontier Optima, EC + Brig, SC — 98.5 and 99.4%, Dual Gold, EC + Estamp, EC — 96.9 and 98.4%, respectively. Somewhat lower efficacy was noted when using the herbicides Dual Gold, EC and Frontier Optima, EC individually: the number of weed plants decreased by 87.4–88.7%, and their mass — by 86.3–89.4%. In the variant using the Frontier Optima, EC herbicide, an increase in the vegetative mass of field pennycress (+ 50% relative to the non-weeded control) was observed, while with the application of Dual Gold, EC, the mass of field pennycress decreased by only 10%.

The highest yield of green mass of the corn and sunflower mixture was obtained using the herbicides Extracorn, SE; Estamp, EC; and the tank mixture Dual Gold, EC + Estamp, EC. In the variant using the herbicide Pronit, EC at an application rate of 3.0 l/ha, the yield of the green mass of the corn and sunflower mixture was 412.7 centners/ha.

When using the herbicide Racer, EC, the yield of the green mass of the corn and sunflower mixture was at the level of the yield of the variant with the application of the reference herbicide Gesagard, SC – 334.5 and 339.2 centners/ha, respectively. As a result of the application of the tank mixture Frontier Optima, EC + Brig, SC, the saved yield of corn green mass amounted to

100.4 centners/ha, sunflower – 155.9 centners/ha, the yield of the corn and sunflower mixture – 425.5 centners/ha. Good sunflower yield indicators were observed in the variant with the use of Frontier Optima, EC + Estamp, EC – 237.4 centners/ha, the yield of the mixture – 392.6 centners/ha. Table 1 – Efficiency of pre-emergence application of herbicides and tank mixtures in mixed crops of corn and sunflower one month after treatment (field trial, RUE "Institute of Plant Protection", 2021)

Variant | Common lambsquarters | Wild buckwheat | Shepherd's purse | Scentless mayweed | Cornflower | Field pennycress | All weeds (pcs./m2) 103.0 16.0 7.0 128.0 13.0 4.0 5.0 319.0 Control (g/m2) 113.0 8.0 16.0 110.0 8.0 5.0 7.0 322.0 without weeding Gesagard, SC – 96.7

100 100 100 100 100 100 100 4.0 l/ha (reference) 98.5 Extracorn, SE – 95.8

100 100 100 100 100 100 100 4.0 l/ha 91.1 Herbisan, SE – 98.7

100 100 100 100 100 100 100 4.0 l/ha 99.4 Adengo, SC – 98.1

100 100 100 100 100 100 100 0.4 l/ha 98.8 Racer, EC – 98.1

100 100 100 100 100 100 100 2.0 l/ha 99.4 Estamp, EC – 62.5 99.4

100 100 100 100 100 100 5.0 l/ha 85.0 99.7 Dual Gold, EC – 92.9 42.9 +50.0* 88.7

100 100 100 100 1.6 l/ha 98.1 87.5 10.0 86.3 Dual Gold, EC +

62.5 96.9 Estamp, EC – 1.6 + 100 100 100 100 100 100

85.0 98.4 4.0 l/ha Frontier Optima, 95.0 +14.3* +125.0* 87.4

100 100 100 100 EC – 1.0 l/ha 85.0 87.5 +50.0* 89.4 Frontier Optima,

98.5 EC + Brig, SC – 100 100 100 100 100 100 100

99.4 1.0 + 2.0 l/ha Frontier Optima,

25.0 95.0 EC + Estamp, EC – 100 100 100 100 100 100

70.0 97.5 1.0 + 3.0 l/ha Pronit, EC – 80.0 45.0 77.5

100 100 100 100 100 3.0 l/ha 71.0 32.0 81.3 Pronit, EC +

97.5 Aegida, SC – 3.0 + 100 100 100 100 100 100 100

99.7 0.3 l/ha Notes: the numerator – reduction in the number of weeds, the denominator – reduction in their mass. * – increase, % of control without weeding

Table 2 – Economic efficiency of pre-emergence application of herbicides in mixed crops of corn and sunflower (field trial, RUE "Institute of Plant Protection", 2021)

Green mass yield, centners/ha Saved yield, centners/ha

Variant | Total | incl. Corn | Sunflower | Corn | Sunflower | Control without weeding 169.2 88.9 80.3 – – Gesagard, SC – 4.0 l/ha (reference) 339.2 182.1 157.1 93.2 76.8 Extracorn, SE – 4.0 l/ha 442.6 157.1 285.5 68.2 205.2 Herbisan, SE – 4.0 l/ha 316.4 316.4 – 227.5 – Adengo, SC – 0.4 l/ha 333.1 333.1 – 244.2 – Racer, EC – 2.0 l/ha 334.5 144.7 189.8 55.8 109.5 Estamp, EC – 5.0 l/ha 433.6 165.3 268.3 76.4 188.0 Dual Gold, EC – 1.6 l/ha 354.9 150.9 204.0 62.0 123.7 Dual Gold, EC + Estamp, EC –

441.0 160.0 281.0 71.1 200.7 1.6 + 4.0 l/ha Frontier Optima, EC – 1.0 l/ha 348.2 145.0 203.2 56.1 122.9 Frontier Optima, EC + Brig,

425.5 189.3 236.2 100.4 155.9 SC – 1.0 + 2.0 l/ha Frontier Optima, EC +

392.6 155.2 237.4 66.3 157.1 Estamp, EC – 1.0 + 3.0 l/ha Pronit, EC – 3.0 l/ha 412.7 140.1 272.6 51.2 192.3 Pronit, EC + Aegida, SC – 3.0

206.1 206.1 – 117.2 – + 0.3 l/ha LSD05 31.8 43.3

In industrial trials, with pre-emergence application of herbicides Extracorn, SE (4.0 l/ha), Stomp Professional, CS (3.0 l/ha) and the tank mixture Dual Gold, EC + Stomp Professional, CS (1.6 + 2.0 l/ha), the number of all annual weeds one month after application decreased by 73.4–75.7%, and vegetative mass – by 84.4–86.5%. The number of common lambsquarters decreased by 73.3–80.0%, mass – by 84.3–88.3%, wild buckwheat – by 0–42.3%, vegetative mass – by 78.2–89.3%. Shepherd's purse, scentless mayweed, and cornflower died completely (100%).

The maximum yield of green mass in the mixed corn and sunflower crop (336.3 centners/ha) was obtained in the variant with the application of the herbicide tank mixture Dual Gold, EC + Stomp Professional, CS. In the variant with the use of the herbicide Extracorn, SE, the yield of the mixture was 318.3 centners/ha, and with the use of Stomp Professional, CS – 307.0 centners/ha.

Table 3 – Efficiency of pre-emergence application of herbicides and a tank mixture on weed infestation in mixed crops of corn and sunflower one month after treatment (industrial trial, UKSP "Sovkhoz 'Dobrovolec'", Klichev district, 2023)

Variant | Common lambsquarters | Wild buckwheat | Shepherd's purse | Scentless mayweed | Cornflower | Field pennycress | All annual weeds Control without (pcs./m2) 153.0 105.0 9.0 5.0 3.0 2.0 3.0 296.0 weeding (g/m2) 639.0 301.0 69.0 13.0 6.0 7.0 6.0 1085.0 Extracorn, SE – 73.3 72.0 42.3 73.4

100 100 100 100 4.0 l/ha 84.3 83.4 78.2 84.4 Stomp Professional, 80.0 68.8 30.8 75.7

100 100 100 100 CS – 3.0 l/ha 87.9 81.1 89.3 86.5 Dual Gold, EC +

79.6 74.2 0 20.0 73.5 Stomp Professional, 100 100 100

88.3 82.3 86.9 50.0 86.1 CS – 1.6 + 2.0 l/ha Note: the numerator – reduction in the number of weeds, the denominator – reduction in their mass.

Table 4 – Economic efficiency of pre-emergence herbicide application and a tank mixture in mixed crops of corn and sunflower (industrial trial, UKSP "Sovkhoz 'Dobrovolec'", Klichev district, 2023)

Green mass yield, centners/ha Saved yield, centners/ha

Variant | Total | incl. Corn | Sunflower | Corn | Sunflower | Control without weeding 86.0 39.1 46.9 – – Extracorn, SE – 4.0 l/ha 318.3 184.2 134.1 145.1 87.2 Stomp Professional, CS – 3.0 l/ha 307.0 170.9 136.1 131.8 89.2 Dual Gold, EC + Stomp Professional,

336.3 187.7 148.6 148.6 101.7 nal, MKS – 1.6 + 2.0 l/ha NSR05 17.9 14.8

Conclusion. In mixed plantings of maize and sunflower, the efficiency of pre-emergent application of herbicides and tank mixtures in small-plot experiments was high, amounting to 77.5–99.4% by number and 81.3–99.7% by mass; in production experiments, it was 73.4–75.7% and 84.4–86.5%, respectively.

The maximum yield of green mass of the mixture in small-plot experiments was obtained in the variant with the application of the herbicide Extracorn, SE (442.6 c/ha), and in production experiments – with the application of the tank mixture Dual Gold, EC + Stomp Professional, MKS (336.3 c/ha).

Thus, pre-emergent weeding of mixed plantings of maize and sunflower increases the efficiency of the entire system as a whole, while increasing the yield and quality of the produce.

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N. S. Stashkevich, А. V. Stashkevich, L. I. Soroka RUE «Institute of Plant Protection», Priluki, Minsk region

EFFICIENCY OF HERBICIDES AND THEIR SPRAY MIXTURES WITH PRE-EMERGENT APPLICATION TO THE MIXED PLANTINGS OF MAIZE AND SUNFLOWER

Annotation. The paper presents the results of studying biological and economic efficiency of the herbicides Gesagard, SC, Extracorn, SE, Brig, SC, Racer, EC, Pronit, EC, Dual Gold, EC, Estamp, EC, Frontier Optima, EC and their spray mixtures with the pre-emergent application to the mixed plantings of maize and sunflower.

Key words: maize, sunflower, weeds, herbicide, spray mixtures, efficiency.