Baking soda is a good remedy for preventing and treating flower diseases

Bordeaux mixture is a mineral-source pesticide and a fungicide advocated for use in the production of green fruit; it has a very good control effect on pear ring rot, black spot, and scab. However, many fruit growers often operate improperly during preparation and use, causing reduced efficacy and even phytotoxicity. The correct method for using Bordeaux mixture in pear orchards is introduced as follows:

(1) Preparation ratio: For use on pear trees, the ratio of copper sulfate, quicklime, and water at 1:4:2000 gives the best effect; appropriately increasing the amount of lime can improve the adhesion of the spray solution, and each spray can last 30-40 days. During the entire pear tree growing period (April to September), spraying only 3-4 times is sufficient, and it has no adverse effect on fruit appearance and does not produce fruit russeting. In contrast, using the traditional 1:2:200 Bordeaux mixture, each spray can only last 15-20 days, and it easily produces fruit russeting. If the amount of lime exceeds this, at 1:6:200 Bordeaux mixture, it affects leaf photosynthesis and the efficacy is also reduced.

(2) Preparation method: Metal containers should not be used to prepare Bordeaux mixture; wooden barrels, plastic barrels, or ceramic vessels can be used. For lime, white, lightweight, blocky fresh lime should be selected, and lime that has been stored for a long time, powdered, and softened should be avoided. When preparing, first use 2/3 of the water to dilute the copper sulfate and stir thoroughly to dissolve it, then use 1/3 of the water to make the quicklime into a concentrated lime milk, then slowly pour the dilute copper sulfate solution into the concentrated lime milk while stirring. The Bordeaux mixture prepared in this way is a sky-blue colloidal suspension and does not produce precipitate.

(3) Method of use: Bordeaux mixture is a protective fungicide and should be used before disease onset, and spraying should be fine and uniform, with the undersides of leaves sprayed until dripping, while branches and trunks should be sprayed by drenching. For mature pear trees, 150 kg of pesticide per mu per application is appropriate. Spraying should be done on sunny days from 9 a.m. to 4 p.m.; it should be avoided on cloudy days or when there is dew, and in rainy seasons it should preferably be used before rain. In southern regions, the first application on pear trees should be carried out as early as possible 10 days after flowering, that is, in mid-April. Bordeaux mixture is an alkaline pesticide and should be used immediately after preparation; generally, it should not be mixed with other insecticides and fungicides to avoid phytotoxicity; moreover, when using other insecticides and fungicides, they should be spaced 7-10 days apart from Bordeaux mixture, otherwise the efficacy will be reduced. However, Bordeaux mixture can be mixed with Tuzet and can improve efficacy.

However, in pear orchards where Bordeaux mixture has been used for a long time, spider mites tend to cause more severe damage, so from May to July, before using Bordeaux mixture, the whole orchard should first be sprayed once with 73% propargite at 1800 times dilution, or 20% dicofol at 800 times dilution.