How to Get the Timing and Chemical Choice Right for Corn Growth Regulation

AbstractTiming of chemical growth regulation in corn: the growth retardant is applied at the 8-10 leaf stage of corn, that is, the early jointing stage of corn. Common types of chemical growth regulators for corn: corn vigorous-growth agent, ethephon, mepiquat chloride, chlormequat, paclobutrazol, amino acid fresh lipid, etc. Generally, a mixed agent is used to achieve a combination of fast-acting and long-lasting effects, and it is less affected by weather, with outstanding growth control and yield increase, and the chemical regulation time can be moved earlier, with no toxicity and no side effects.

I. Timing of chemical growth regulation in corn

1. The timing for using corn growth retardant is the 8-10 leaf stage of corn, that is, from when corn is “a foot or so tall” to when it is “knee high.” This stage is the early jointing stage of corn. Spraying the chemical growth regulator can make the corn stalk thicker, shorten the internodes, and lower the ear height.

2. The number of layers and strands of “brace roots” increases, which can not only effectively prevent corn lodging, but also promote the transport of nutrients to the ear, reducing empty plants and barren tips.

II. Common types of chemical growth regulators for corn

1. The regulators commonly used for chemical growth regulation in corn mainly include corn vigorous-growth agent, ethephon, mepiquat chloride, chlormequat, paclobutrazol, amino acid fresh lipid, etc. Although there are many corn growth control products on the market, they still cannot do without the above ingredients, either as mixed agents or single agents.

2. However, when spraying corn, try not to use single agents, because using single agents has certain side effects, so it is suitable to use mixed agents. Generally, mixed agents can achieve a combination of fast-acting and long-lasting effects, are less affected by weather, have outstanding growth control and yield increase, allow the chemical regulation time to be moved earlier, and are non-toxic with no side effects.

III. Precautions for chemical growth regulation in corn

1. The liquid must be prepared strictly according to the instructions; the concentration of the liquid must not be increased at will.

2. The spraying period must be strictly controlled; it must not be advanced or delayed. Too early will inhibit the normal growth of the plant, while too late will fail to achieve the proper effect of chemical regulation.

3. During this period, do not spray repeatedly or miss spraying. Do not spray in drought. You may spray the upper leaves of the corn; do not spray the whole plant.

4. The liquid should be used as soon as it is prepared; it must not be stored for a long time, and it must not be mixed with pesticides or chemical fertilizers, so as to avoid losing effectiveness.

5. If it rains within 4 hours after spraying, respraying is needed, and when respraying, the amount of chemical should be halved.

6. When applying the chemical, do not smoke, drink water, or eat. After application, promptly wash the skin of the hands, face, and other areas, as well as contaminated clothing.

7. High-yield field plots with high water and fertilizer levels and tolerance to dense planting are suitable for chemical regulation, while medium- and low-yield fields with low fertility, plots with three types of seedlings due to missing plants and replanting, and plots with obviously insufficient biomass for special reasons must not be chemically regulated.

IV. Harm of regulating corn growth too early

If a growth retardant is used on corn before the 8-leaf stage, because the control is too early, the corn stalk will not grow vigorously and the stalk will be too short, so it is recommended to use the growth retardant after the 8-leaf stage.

V. Harm of regulating corn growth too late

If the corn growth retardant is used too late, when the number of leaves exceeds 11, the corn has already passed the jointing stage, and the following problems will occur.

1. It causes incorrect internode shortening in corn: the base 1-3 internodes should have been shortened, but using it too late instead causes the middle 4-5 internodes to be shortened more than the base 1-3 internodes. This not only fails to effectively prevent corn lodging, but also leads to poor corn growth and reduced yield.

2. It affects tassel differentiation in corn: after jointing, the corn tassel begins to differentiate. If corn growth is controlled at this time, it will affect corn tassel differentiation, resulting in a small amount of pollen in the corn tassel, thereby affecting corn pollination and reducing corn yield. Therefore, corn growth regulation must not be done too late.