Twelve Kinds of Common Disease of Crops
The necessary elements of crops will loss during the growth process and which will have different or similar symptoms. At this time it is necessary to pay attention to distinguish the different symptoms of different element deficiency of crops, and apply the fertilizer accordingly so that the crops growth will be healthy.
Now, we should take a look at the specific symptoms of elements deficiency.
Performance part:
The new leaves, terminal buds, fruits, tender part and other part with strong vitality.
Disease performance:
The tip of the blade is partially bent and yellow, foliage folds (parachute) up 
or down, and there is mucus. The top leaves are often dark brown. The terminal buds, lateral buds, apical and other meristems will decay and die and there is “broken neck” symptoms. As for cabbage, it will have leaf disease and dry heart symptom. The roots of plants are often black and rot.
Cabbage dry heart.
Calcium deficiency will make the navel of tomato, pepper, watermelon, eggplant and other plants rot.
Tomato navel rot
Apple appears bitter pox and water heart disease, grapes, watermelons, citrus and other fruit will be cracking.
Apple water heart disease
Performance part:
Leaves, fruits, stems, the upper and lower leaves, the old leaves.
Disease performance:
The plant is short and the leaf shape is distorted. The plant lack of phosphorus too much, the performance part may appear necrotic area. If there is phosphorus deficiency, the old leaves will be affected firstly, especially at low temperatures, phosphorus deficiency plants are common purple or red, stems are purple, loss of luster. The phosphorus deficiency in production often caused by poor roots which affecting phosphorus absorption.
Performance part
Mainly in the old leaves of lower part of the plant.
Disease performance:
The old leaves will be variegated or there are yellow spots of the old leaves, leaf edge will be necrotic. Severe potassium deficiency, the lower part of the old leaves come to green and gradually be necrotic, leaves are dark green and dull. Potassium deficiency symptoms often appear first in the lower leaves, with the lack of aggravation, gradually spread to the top, and usually from the leaf edge began to turn to yellow and dry.
Performance part:
Leaves.
Disease performance:
The growth is inhibited, especially the internode growth
is severely blocked, and the leaves are white.
Typical Symptoms:
Fruit trees: “leaf disease”, “cluster leaf disease”, corn: “albino seedlings”, grape: “big grain” .
Performance part:
Mainly in the old leaves.
Disease performance:
The chlorophyll content decreased, and the emergence of green loss disease. Plant is short and slow to grow. The leaves are yellowing due to chlorophyll degradation. If the magnesium deficiency is severe, only the base of the leaves have green residue.
Performance part:
The tend leaves.
Disease performance:
The symptoms of iron deficiency are similar to magnesium, the difference is that the leaves lack of iron will turn yellow first, the veins are still green, and then whole leaves turn yellow or white.
Performance part:
tender leaves and tissue.
Disease performance:
The symptoms of manganese deficiency is similar to the iron deficiency, there are green spots on veins, and gradually formed stripes, but the veins remain green.
Performance part:
Tender new leaves
Disease performance:
The new leaves are yellow. The deformity of new leaves and there are spots on leaves.
Cabbage molybdenum deficiency
Plant growth is poor, short.
Leguminous plants lack of molybdenum will affect nitrogen fixation, pods are not full
Performance part:
Top stem tip, stem, petiole.
Disease performance:
Stem tip growth is inhibited, and if plant lack boron too much, it will be withering, and even death. Leaves will have the symptoms of becoming thicker and brittle, shrinkage deformed, plant dwarf, stems and petiole easy to crack. Root growth and development is blocked, root is short and dark brown. Genital development is blocked, low seed setting rate, fruit is small, deformity.
Tomato seriously lack of boron will form corky hard fruit
Deformed fruit
Typical symptoms are “flowers and not real”, “buds not to flower” and so on
Performance parts:
Old leaves and new leaves.
Disease performance:
New leaves loss green, old leaves become yellow and dry.
Apple tree lack of nitrogen
Plant growth is slow, thin branches, the top of the new leaves gradually 
become small and easy to fall.
Performance parts:
Tender leaves, shoots growth point
Disease performance:
Leaves are white, new leaves are shrinking, there are white point on new leaves, new leaves and growth point are yellow, leaves are curl.
Performance parts:
New leaves, shoots growth point
Disease performance:
Leaves color will turn to light green, or even become white, extended to the new leaves, leaves are slender, plant is short, flowering delay, the root is elongated.
The article is quoted from: https://www.fert.cn/1005/
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