Causes and Solutions of yield reduction of Jinzao Jujube in Ningxian County in 1999

Jinzao cultivation in Ning County of Gansu Province is concentrated in Zaosheng Town. In 1999, the production area was 100 hectares, and the total output was 212.5 tons. The total output decreased by 22.3 tons on average compared with previous years, and the yield decreased by 12.5%. It was a year with poor output in history.

1. Reasons for Jinzao's Yield Reduction

1. Jujube leprosy is serious: According to the adjustment in Xinzhuang Village, Zaosheng Town, Ning County, before 1997, the disease rate of jujube leprosy accounted for 3.98% of the total number of plants, and the infected trees were all fruit trees. By 1999, the number of jujube trees infected with leprosy had risen to 1387, accounting for 10.05% of the total number of trees, 2.2 times that of 1997. Every year the town due to jujube disease cut down about 2600 hanging fruit trees.

2, flowering rain damage: April to June 1999, when jujube flowering, affected by three consecutive four days of low temperature and rain, of which the second low temperature and rain weather appeared in May 20 - 25, rainfall reached 198.5 mm, the average temperature of 22.50C. Due to the low humidity in the early stage, the second flower stage was delayed by 10 days compared with the average date, and the full bloom appeared on May 18 - 24. Besides affecting pollination, some flower organs were mechanically damaged by raindrops due to rainfall. After rain, the transpiration was intensified due to the sudden rise of temperature, and stigma, stamens and young leaves wilted. The rate of flower and fruit dropping reached 88.5%.

3. Extensive management: jujube farmers in jujube area have never applied fertilizer to jujube trees, let alone pruned and prevented diseases and insect pests. The ground is managed only for intercropping, resulting in low yields and severe size.

4. Single variety: Jinzao is the variety in Zaosheng Town. The pollen vigor of Jinzao is not strong and the fruit setting rate is low.

II. Ways to improve yield

1, scientific fertilization: in view of the jujube garden soil barren, poor fertility characteristics, fertilizer use requirements centralized batch, and the amount should be large, nutrients should be comprehensive, the fertilization of dense jujube high-yield garden is more important. 3 - 5 years old jujube garden fertilizer 35 - 40 kg, calcium superphosphate 0.5 - 1.0 kg, potassium 0.3 - 0.5 kg. At the same time, in jujube leaves, flowering pollination, timely topdressing urea. The first time in mid-late May, 0.1 - 0.2 kg urea per plant; the second time in mid-late June, 0.3 - 0.4 kg urea per plant; the third time in mid-late July, 0.3 - 0.4 kg urea per plant to promote fruit expansion and coloring. In addition, foliar fertilizer should be sprayed once every 20 - 30 days during the growing season, for a total of 4 - 6 times. After harvesting crops between rows, stems return to the field to improve soil fertility.

2. Reasonable pruning: jujube tree adopts natural semicircle shape with multiple main branches. The trunk is 80 - 100 cm high, the main branch is 3 - 4, and each main branch is equipped with 2 - 5 branches. In view of the problems of closed crown, dense branches and poor ventilation and light transmission caused by years of allowed growth in local jujube orchard, winter pruning is mainly to renew and rejuvenate jujube heads in order to prolong their fruiting years, and to cut off cross branches, dense branches, drooping branches, diseased branches and dead branches emphatically, while retaining healthy branches, empty branches, peripheral branches and oblique branches. The erect shoots with space in the crown can be cut short and cultured into fruiting shoot groups. The number of new dates per tree was adjusted to 20 - 30 by winter pruning. After germination, all the dry branches that do not germinate are cut off and burned intensively.

Summer pruning is carried out from late May to late June, cutting off excessive sprouts in the bore in time, cutting off the new shoots sprouted on the jujube strands and the excessive long branches sprouted at the base of the jujube head in time before the branches are lignified, so as to reduce the consumption of nutrients, improve the fruit setting rate and improve the lighting conditions. In June, the date head should be removed. Weak branches light topping, strong branches heavy topping or multiple topping, in order to control the growth of jujube head. After topping, the secondary branches and branches were strengthened, which had obvious effects on increasing fruit setting rate and promoting fruit development.

3. Flower protection and fruit protection: releasing bees at flowering stage of jujube garden can reduce flower drop caused by unpollination or poor pollination. Spraying gibberellin 10 - 15PPM once in full bloom can improve the fruit setting rate. It can also be sprayed with 5 - 10PPM 2.4-D at flowering stage and 30-60PPM 2.4-D after flowering, which can increase fruit setting rate and reduce fruit drop. 0.1%--0.3% boric acid or borax can also be sprayed at flowering stage to improve fruit setting rate. There are also measures such as girdling and ring cutting, which can improve the fruit setting rate.

4, drought resistance and drought resistance: drought years, can be in the germination, fruit speed long term, late autumn and early winter combined with fertilization of the whole garden irrigation 3 - 4 times, or dry period combined with spraying 400 - 500 times of "dry land dragon" drought resistance agent, or spray after drought to save, the agent can be selected 1.8% love more than 6000 plus green Fenwei No. 1 or No. 2 1000 times crown spray.

5, loose soil weeding: in order to reduce soil consumption, after each heavy rain or watering, until the soil white when loose soil. Insist on hoeing grass in tree tray to prevent grass shortage.

6. Strengthen the prevention and control of jujube leprosy: use a period of time after fruit picking to strengthen management. Heavy application of calcium superphosphate, elimination of weeds in and around the jujube garden and digging roots and tillers, painting white trunks, sawing off diseased branches, drilling holes in the roots of infected trees, connecting rubber tubes, dripping or injecting 1000PPM tetracycline or oxytetracycline 500 ml into the trees, generally twice, the disease can be alleviated.