Major Heat Farming

During Major Heat, crops across Northeast China enter a critical stage of yield formation. Maize at tasseling and silking, rice at heading and flowering, and soybeans at pod setting and seed filling all advance simultaneously, bringing field management into the most critical period of the year.
Maize management during tasseling and silking. Spring maize in Northeast China enters tasseling and silking during Major Heat, with tassels emerging, silks appearing from female ears, and pollination and kernel formation beginning. This is the key stage for determining kernels per ear and also the crop’s critical period of water demand. Management centers on ensuring water supply, because drought during tasseling and silking can cause poor pollination and a severe decline in kernel number. Where soil moisture is insufficient, irrigation should be applied immediately at 30–40 cubic meters per *mu*. 穗肥 is applied at 5–8 kilograms of urea per *mu* to promote kernel development. Under rainy or excessively hot conditions, artificial supplementary pollination may be used by gently shaking tassels between 9:00 and 11:00 a.m. to improve seed set. Corn borer enters a key treatment window and is controlled using phoxim or Bt preparations, while aphids, leaf spot, northern corn leaf blight, and other problems require simultaneous monitoring. Management during tasseling and silking directly affects kernels per ear and final yield.
Rice management during heading and flowering. Rice in Northeast China enters heading and flowering during Major Heat, with young panicles emerging and flowering and pollination beginning. This is the key stage for determining seed-setting rate. Management centers on maintaining a shallow water layer of 3–5 centimeters without allowing fields to dry; applying 穗肥, mainly potash, at 3–5 kilograms of potassium chloride per *mu* to promote flowering, seed set, and grain development; and monitoring weather closely. Persistent cloudy and rainy conditions during heading and flowering can impair pollination and seed set, while temperatures of 35°C or above can render pollen inactive and increase the number of unfilled grains. Rice blast, sheath blight, planthoppers, and the striped stem borer enter critical treatment windows. Panicle-neck blast is one of the most important rice diseases and requires one application of tricyclazole before heading and another after full heading. Management during heading and flowering directly affects seed-setting rate and final yield.
Soybean management during pod setting and seed filling. Soybeans in Northeast China enter pod setting and seed filling during Major Heat, with pods developing and seeds becoming full. This is a critical stage for determining seed number and thousand-seed weight. Management centers on applying 结荚肥, mainly potash, at 3–5 kilograms of potassium sulfate per *mu* to promote full seed development; ensuring sufficient water because drought can cause pod drop and poorly filled seeds; controlling soybean pod borer, aphids, leaf spot, frogeye leaf spot, and other pests and diseases as they enter key treatment windows; and topping at the proper time to control excessive vegetative growth and direct more nutrients toward pods. Management during pod setting and seed filling directly affects seed number and thousand-seed weight.
Pasture management. Pastures in eastern Inner Mongolia remain in vigorous growth and livestock grazing continues. Herders implement rotational grazing systems to make rational use of grassland resources.

During Major Heat, Northwest China enters a critical stage of summer management: spring wheat moves from grain filling into maturity, cotton enters flowering and boll formation, and orchards move from fruit enlargement toward maturity.
Spring-wheat management from grain filling to maturity. In the Hexi Corridor of Gansu and the Yellow River irrigation districts of Ningxia, spring wheat moves from grain filling toward maturity during Major Heat. Kernels become full, ears begin to yellow, and maturity approaches. This is the final stage determining thousand-kernel weight. Management centers on ensuring water supply because drought during grain filling can severely reduce thousand-kernel weight; where soil moisture is insufficient, irrigation should be applied promptly at 30–40 cubic meters per *mu*. 干热风 should be prevented through foliar fertilizer applications that improve stress resistance. Wheat rust, aphids, and other problems enter the final stage of control. Harvest should be carried out at the proper time, taking advantage of clear weather once ears have turned fully yellow and kernels are full and hard. Management during grain filling directly affects thousand-kernel weight and final yield.
Cotton management during flowering and boll formation. Cotton across Xinjiang enters flowering and boll formation during Major Heat, with flowering and boll setting occurring simultaneously. This is the key stage for determining boll number and yield. Management centers on applying 花铃肥 at 10–15 kilograms of compound fertilizer per *mu* to promote flowering, boll setting, and boll development; timely pruning through topping, removal of lateral growing points, and removal of unwanted shoots to control vegetative growth and promote reproductive growth. Topping is one of the most important techniques in cotton management and is generally carried out in mid- to late July. Cotton bollworm, aphids, cotton spider mites, Fusarium wilt, Verticillium wilt, and other pests and diseases enter key treatment windows, with cotton bollworm requiring particular attention during flowering and boll formation. Adequate water must also be ensured, because drought during this stage can cause flowers and bolls to drop. Management during flowering and boll formation directly affects boll number and final yield.
Orchard management. Apples, fragrant pears, grapes, and other fruit crops in southern Xinjiang move from fruit enlargement toward maturity. Apples and pears enter peak enlargement and require stronger water and nutrient management through 膨果肥, mainly potash, together with control of codling moth, oriental fruit moth, spider mites, and other pests. Grapes enter veraison, with berries beginning to change color and accumulate sugar, and require stronger water and nutrient management through potash applications that promote sugar accumulation and coloring, together with control of downy mildew, powdery mildew, gray mold, and other diseases.
Specialty crops. Potatoes around Dingxi, Gansu, move from peak tuber enlargement toward maturity and require stronger water and nutrient management and late-blight control. Goji in Ningxia enters peak maturity and harvest, and farmers seize clear weather for picking and drying. Processing tomatoes in Xinjiang enter maturity and harvest, with farmers taking advantage of clear weather to bring in the crop.

During Major Heat, North China enters a critical stage of summer management. Summer maize enters tasseling and silking, spring maize enters grain filling, water and nutrient demand reaches its annual peak, and the critical “七下八上” flood-control period begins.
Summer-maize management during tasseling and silking. Summer maize in North China enters tasseling and silking during Major Heat, with tassels emerging, silks appearing from female ears, and pollination and kernel formation beginning. This is the decisive stage for kernels per ear and the crop’s critical period of water demand. Water supply must be secured because drought at this stage can cause poor pollination and a severe reduction in kernel number. Where soil moisture is insufficient, irrigation should be applied immediately at 30–40 cubic meters per *mu*. 穗肥 is applied at 5–8 kilograms of urea per *mu* to promote kernel development. Under rainy or excessively hot weather, artificial supplementary pollination may be used to improve seed set. Corn borer enters a key treatment window and is controlled with phoxim or Bt preparations, while aphids, leaf spot, northern corn leaf blight, and other problems require simultaneous monitoring. Management during tasseling and silking directly affects kernel number and final yield.
Spring-maize management during grain filling. Spring maize in North China enters grain filling during Major Heat, with kernels becoming full. This is a critical stage for determining thousand-kernel weight. Management centers on securing water supply because drought during grain filling can reduce thousand-kernel weight and irrigation should be applied promptly when soil moisture is insufficient; controlling corn borer, aphids, leaf spot, and other pests and diseases entering key treatment windows; and preventing premature senescence through foliar fertilizer applications that prolong leaf function and promote grain filling. Management during grain filling directly affects thousand-kernel weight and final yield.
Flood control and drainage. During Major Heat, North China enters the critical “七下八上” flood-control period, when heavy rainfall becomes more frequent and localized flood risk increases. Farmers need to keep field drainage systems unobstructed and prepare drainage in advance for low-lying plots. Dryland crops such as maize and peanuts are intolerant of waterlogging, and standing water lasting more than 48 hours can cause root rot and plant death. Weather forecasts and flood-control warnings therefore require close attention.
Orchard management from fruit enlargement to maturity. Apples, pears, peaches, and other fruit crops across North China move from fruit enlargement toward maturity, with early-ripening peaches, pears, and other cultivars beginning harvest. Growers apply 膨果肥, mainly potash, at 10–15 kilograms of potassium sulfate per *mu* to promote fruit development and improve quality; carry out summer pruning by removing vigorous shoots and overly dense branches to improve ventilation and light penetration; and strengthen control of apple ring rot, anthracnose, pear scab, peach aphids, oriental fruit moth, spider mites, and other pests and diseases entering key treatment windows.
Vegetable management. Open-field vegetables across North China enter rapid growth and peak harvest, with cucumbers, beans, eggplants, peppers, tomatoes, and other summer vegetables reaching the market in large quantities. Water and nutrient management and pest and disease control need to be strengthened. As temperatures continue rising, vegetables also require protection against heat, drought, and sunscald.

During Major Heat, the middle and lower Yangtze enters the busiest agricultural period of the year. The “双抢” rush unfolds fully, with large-scale early-rice harvesting and late-rice transplanting advancing simultaneously, while the region also enters the period of high-temperature midsummer drought.
Large-scale early-rice harvest—the “双抢” rush unfolds fully. Early rice across the Yangtze River basin enters large-scale harvest during Major Heat, with panicles turning completely yellow, kernels becoming full and hard, and physiological maturity being reached. The “双抢” rush enters its busiest stage. Farmers seize clear weather to harvest, with combines operating day and night, and grain is promptly dried and stored after harvest. The early-rice harvest window generally lasts only 5–10 days, so weather forecasts must be followed closely. If a typhoon or heavy rain is approaching, harvest needs to be completed before the rain arrives. Harvesting too late can cause grain shattering or sprouting after rain and result in losses.
Late-rice transplanting expands fully. Immediately after the early-rice harvest, late rice is transplanted, representing the “抢种” component of the “双抢” rush. Transplanting is concentrated between Major Heat and the Beginning of Autumn. After early-rice harvest, fields are immediately plowed and prepared by flooding and soaking, harrowing level, and applying sufficient basal fertilizer. Seedlings aged 20–25 days are transplanted at the “三叶一心” stage. After transplanting, a shallow water layer of 3–5 centimeters is maintained to promote recovery and low-position tillering. The earlier late rice is transplanted, the better: every day of delay shortens the growing period and reduces yield. Transplanting is generally completed before the Beginning of Autumn.
High-temperature midsummer drought and irrigation management. After the end of the plum-rain season, the middle and lower Yangtze shifts into hot midsummer drought conditions during Major Heat, with reduced rainfall, rising temperatures, and strong evaporation. Middle-season rice enters booting and heading and requires secure water supply, because water demand is high during this stage and drought can reduce kernels per panicle. Farmers need to inspect irrigation facilities, allocate irrigation water rationally, and give priority to water supply during the booting-to-heading stage of middle-season rice and the post-transplant recovery stage of late rice.
Pest and disease control. High temperatures and humidity during Major Heat bring rice pests and diseases into a high-incidence period. Key targets include rice blast, especially panicle-neck blast, treated with tricyclazole or isoprothiolane; sheath blight, treated with validamycin or difenoconazole + propiconazole; rice planthoppers, treated with imidacloprid or buprofezin; stem borers, treated with dimehypo or Bt preparations; and rice leaf roller, treated with abamectin or emamectin benzoate. Farmers need to strengthen field inspections and intervene promptly when pests or diseases are detected.
Vegetables and aquaculture. The Yangtze River basin enters the hot midsummer drought period, and open-field vegetable growth is affected by heat and drought, requiring stronger irrigation and shading for cooling. Greenhouse vegetables need improved ventilation, cooling, and pest and disease control. In aquaculture, fish feed actively during the hot season but are also prone to oxygen depletion, pond overturning, and disease outbreaks, requiring stronger aeration, water-quality management, and disease prevention.

During Major Heat, agricultural activities across Southwest China enter a critical stage of summer management. Middle-season rice enters booting and heading, spring maize enters grain filling, and potatoes move from tuber enlargement toward maturity.
Middle-season rice management from booting to heading. Middle-season rice in Southwest China enters booting and heading during Major Heat, with young panicles completing their final stage of development and beginning to emerge and flower. This is a critical stage for determining kernels per panicle and seed-setting rate. Management centers on maintaining a shallow water layer of 3–5 centimeters without allowing fields to dry; applying 穗肥, mainly potash, at 3–5 kilograms of potassium chloride per *mu*; and controlling rice blast, sheath blight, planthoppers, and other pests and diseases entering key treatment windows. Weather also requires close attention, because persistent cloudy and rainy conditions during heading and flowering can impair pollination and seed set, while temperatures of 35°C or above can render pollen inactive.
Spring-maize management during grain filling. Spring maize in Southwest China enters grain filling during Major Heat, with kernels becoming full. This is a critical stage for determining thousand-kernel weight. Water supply must be secured because drought during grain filling can reduce thousand-kernel weight. Corn borer, aphids, leaf spot, and other pests and diseases require control, while premature senescence should be prevented through foliar fertilizer applications that prolong leaf function.
Potato management from tuber enlargement to maturity. Spring potatoes in the main producing areas of Yunnan, Guizhou, and Sichuan move from peak tuber enlargement toward maturity during Major Heat, with underground tubers expanding rapidly and some early cultivars beginning to mature. Management centers on applying 结薯肥, mainly potash, at 8–10 kilograms of potassium sulfate per *mu*; controlling late blight with mancozeb or metalaxyl; and harvesting at the proper time, with early cultivars beginning to be lifted when aboveground plant parts start to yellow, followed by prompt drying and storage.
Orchard and tea-garden management. Citrus-growing areas across Southwest China enter fruit enlargement and require stronger water and nutrient management through 膨果肥, mainly potash, together with control of citrus red mites, leaf miners, canker, anthracnose, and other pests and diseases. Summer tea-garden management continues through pruning after summer-tea picking, fertilization, and pest and disease control.

#### (1) Mainland South China
Peak late-rice transplanting. Late rice across South China enters peak transplanting during Major Heat, with seedlings reaching transplanting standards at 20–25 days of age and the “三叶一心” stage, and large-scale transplanting into the main field begins. Fields need to be prepared carefully before transplanting through flooding and soaking, harrowing level, and sufficient basal fertilizer at 20–25 kilograms of compound fertilizer per *mu*. Transplanting density depends on cultivar and is generally 15,000–18,000 hills per *mu*. After transplanting, a shallow water layer of 3–5 centimeters is maintained to promote recovery and low-position tillering. Late-rice transplanting is one of the key links in annual rice production, and transplanting quality directly affects effective panicle number and final yield.
Early-rice harvest largely complete. By Major Heat, the early-rice harvest in South China is largely finished, with grain safely stored and early-rice fields fully plowed and prepared for late-rice transplanting. The “双抢” rush reaches its busiest stage, with harvesting and planting advancing simultaneously.
Peak “双抢” rush. The South China “双抢”—urgent harvesting of early rice and urgent planting of late rice—reaches its busiest stage during Major Heat. Farmers need to complete early-rice harvesting and late-rice transplanting within a short period, under tight schedules, heavy workloads, and intense heat. Labor must be organized efficiently, with harvest accelerated during clear weather and transplanting carried out without delay to ensure that early rice is safely stored and late rice is planted on time.
Typhoon preparedness. South China enters the peak of active typhoon season during Major Heat. Strong winds and torrential rain associated with typhoons can lodge rice, cause fruit drop, damage greenhouse structures, and harm aquaculture. Farmers need to follow typhoon warnings closely and prepare in advance by harvesting mature crops, reinforcing greenhouse structures, checking drainage systems, and preparing aquaculture operations for flooding.
Tropical-fruit management. Lychee harvesting is largely complete, including the completion of harvest for middle- and late-season cultivars. Postharvest pruning and fertilization are carried out immediately to restore tree vigor and promote autumn-shoot emergence. Mango harvest moves from its peak toward the final stage. Longan enters maturity and harvest as fruit reaches full ripeness. Citrus enters fruit enlargement and requires control of excessive summer-shoot growth together with citrus red mites, leaf miners, canker, and other pests and diseases. Bananas in Guangdong, Guangxi, and Hainan enter flowering and fruiting and require stronger water and nutrient management.
Vegetables and aquaculture. Open-field vegetables across South China enter rapid growth and peak harvest. Rising temperatures bring pests and diseases into a high-incidence period and require stronger control. In aquaculture, the hot season requires stronger aeration, water-quality management, and disease prevention, while the typhoon season brings added flood risk.
#### (2) Taiwan
Rice: In central Taiwan—including Changhua, Yunlin, and the Chianan Plain—the first rice crop has been fully harvested and the second crop enters tillering management. In southern Taiwan, particularly the Kaohsiung–Pingtung region, the second rice crop enters peak tillering. In northern Taiwan, including Taoyuan and Hsinchu, the first rice crop enters the final stage of harvest while transplanting begins for the second crop.
Vegetables: During Major Heat, summer vegetables across Taiwan enter peak harvest, with cucurbits such as watermelon, cucumber, and muskmelon, together with beans and fruiting vegetables, reaching the market in large quantities. Vegetable production is affected by high temperatures and requires stronger irrigation and pest and disease control.
Fruit trees: Mango harvesting moves from its peak toward the final stage. Lychee harvesting is largely complete. Citrus enters fruit enlargement. Bananas in southern Taiwan enter flowering and fruiting.
Tea: Summer management continues across tea gardens in central and southern regions such as Nantou and Chiayi and in northern tea districts such as Wenshan and Sanxia. Summer-tea picking begins.
Fisheries: Fishing continues in waters around Taiwan during Major Heat. With typhoon season underway, coastal areas prepare for typhoon protection.
Farmer’s proverbs and folk customs: Taiwanese folk tradition preserves the saying “大暑吃鳳梨”—pineapples are abundant during Major Heat and are eaten to cool the body and relieve thirst. Another saying, “大暑熱，透心涼”, describes the intense heat of Major Heat and the custom of eating chilled foods for relief. Major Heat also falls within the “中伏” period, and folk custom preserves the dietary saying “头伏饺子二伏面”, associating dumplings with the first *fu* period and noodles with the second.