DE1013459B - Agent for selective weed control in crops - Google Patents

Description

Means for selective weed control in crops. For weed control in agricultural and horticultural crops, efforts are made to achieve those with high Expenditure of time and manpower related mechanical methods by using to replace chemical agents.

A means that is used in the pre- or post-emergence method for weed control is to be used, a number of requirements must be made, which the Make the selection of such substances appear very limited. So the cultures are allowed not be affected; the protection should continue to hold up until the plants are so strengthened that the weeds that are now emerging are suppressed. Hence the ever increasing importance of a reliable chemical Weed control comes to the endeavor to use such herbicides that act selectively and whose effects are lasting.

It has now been found that isatin or its substitution compounds of the general formula where R can stand for one or more alkyl groups and / or halogen, can be used as selective weed control agents. .

The compounds exert an excellent selective effect on dicots Plant out with complete sparing of the Gramineae. Are particularly prominent these properties in isatin, 4-chloro-isatin, 5-chloro-isatin, 6-chloro-isatin, 7-chloro-isatin, S-chloro-6-methyl-isatin, 6-chloro-7-methyl-isatin, 5, 7-dichloro-isatin, 4, 7-dichloroisatin, 4, 5, 7-trichloroisatin, 5-bromo-isatin and 5, 7-dibromoisatin.

It consists of. suitable choice of substitution products a large Diversity of the mode of action, whereby the scope is by no means only is limited to a few weeds and crops.

The agents to be used according to the invention are pronounced root toxins and only come into effect in the soil when they are removed from the plants with the help of the Roots are added. If the substances are given as so-called pre-emergence, so It is true that in many cases the germination of the seeds and the emergence of the plants does not prevent the young broad-leaved plants, however, from taking care and dying as soon as they are forced to feed through the roots. You give the Means as so-called post-emergence, z. B. in the spray or dust process, so the green parts of the plants, which are sensitive to the roots, are not damaged. Against many herbicides that are on the way over the above-ground parts develop their effect, has a number of the plants to be protected in some particularly sensitive parts and in certain stages of development, e.g. B. the Whip stage of the onions, so sensitive that even selective Funds can only be used to a limited extent in these cases. Since now the mentioned Isatins do not penetrate the green parts of the plants and they are therefore undamaged one recognizes the significant advantage of this class of substances in one application in the post-emergence spraying or dusting process.

Some growth regulators have become known that make their herbicidal Develop character by hormonal means as growth inhibitors or growth inhibitors. These Substances have a toxic effect on all parts of the sensitive plants and are also considered to be selective herbicides have been proposed. The funds at hand do not have the dreaded disadvantages of these substances, such as this Causing deformities on the root neck and ears of cereals.

The agents to be used according to the invention are practically insoluble in water and have a long residence time while maintaining their herbicidal properties in the ground. This makes it possible to use selective weed control in the pre-, and post-emergence processes to achieve a lasting effect. On the other hand lies the time of action always only within one vegetation period, so that with crop rotation Cultivated plants that are sensitive to isatins are not damaged.

Finally, the above-mentioned isatins can be mixed with substances, that increase their scope of action.

The application of isatin compounds as pre-emergence occurs on most advantageous in dilution with fillers through superficial Work into the soil before sowing the seeds. The application after however, emergence is better with the usual littering, dusting and spraying methods.

Example 1 In boxes 30 cm long, 25 cm wide and 6 cm deep the soil was superficially with the active ingredient, which was used for better application 60% talc was cut, mixed, and the following sowing was carried out: three rows of oats (Avena sativa) of fifteen grains each, two rows of beans (Vicia faba) with ten grains each, 1.5 g each of rapeseed (Brassica napus), mustard (Sinapis arvensis) and Cress (Lepidium sativum) were sown broadly.

The following tables result from a series of six such experiments. Table 1 Average number of seeds accrued, 14 days after sowing Active ingredient g / ma Small-seeded weeds Large-seeded plants Mustard I rapeseed I cress Bean oats 5, 7-dichloroisatin. . . . . . . . . . . . . . . . . . . . . . 5 80 75! 0 70 91 8 95 70 0 20 92 10 90 80 0 25 91 Isatin ............................... 9 60! 80 20 100 75 12 45 43 12 50 95 15 30 38 6 50 90 20 33 31 0 0 I 95 Control (talc only) ................. 10 100 100 100 100 100 In the following table it was noted which percentage of these emerged plants died again in the further course of the test series. Table 2 Dead plants in%, based on the seeds that emerged after 14 days, after 35 days or in brackets after 50 days. X means that the plants have not died completely, but are so badly damaged that they no longer arise. ( Small-seeded weeds Large-seeded plants State of growth Longitudinal Active ingredient g / m # of Mustard I rapeseed cress bean I oat oat plants I. 5, 7-dichloroisatin 5 100 100 i - 0 (100) 0 (0) healthy 'normal 8 100 100 - 0 (100) 3.5 (3.5) healthy normal 10 100 i 100 - 100 5 (5) healthy, slightly behind of control return I. Isatin 9 100 100 100 O, X (O, X); 0 (0) healthy normal 12 100 100 100 O, X (0, X)! 0 (0) healthy normal 15 100 I 100 100 O, X (0, X) 0 (0) healthy normal 20 100 (100 - - 0 (0) healthy normal Control 10 0 (0) l 0 (0) 0 (0) 0 (0) j 0 (0) healthy I normal The weeds mentioned can thus be combated with success in oat crops.

Example 2 In bed trials, 5,7-dichloroisatin was used in an analogous manner as in Example 1 effective against shepherd's purse (Capsella bursa-pastoris), rapeseed and mustard with complete sparing of wheat (Triticum sativum), maize (Zea Mays) and barley (Hordeum sativum).

Example 3 In pot tests, as in Example 1, beans and oats were produced treated with 4-chloro- and 6-chloro-isatin. At an application rate of 6 g / m2 was in the case of oats there was no difference to the control plants, while only completely deformed and a few millimeters high seedlings from the seeds of the bean which died after 5 weeks.

Example 4 showed 4, 7-dichloroisatin when used analogously as in Example 3 no damage to the oats, while the seeds of the bean were severely malformed Plants emerged that were only a few centimeters high and die after 4 weeks began.

7-chloro-isatin behaved in the same way. Example 5 caused 5-bromo-isatin in the pre-emergence process analogous to Examples 1 and 3 with one application rate from 4.5 g / m2 no damage to the oats, on the other hand peas (Pisum sativum) and beans ran only in a severely damaged and no longer fit for life.

Claims (1)

PATENT CLAIM: Agent for selective weed control, characterized by its isatin content or its substitution products of the formula where R can stand for one or more alkyl groups and / or halogen.