As you sit comfortably, sipping your tea while bundled up in all the clothes from your wardrobe, remember that your crops and investment stand resilient, battling the cold and rain. They resist and shiver, struggling physiologically with the chaos happening inside them.
#First: Let’s understand what’s happening inside the plants under cold, wet weather conditions. This is also for engineers to think about suitable solutions…
- The cytoplasm in cells, such as in root hairs, nearly stops moving at soil temperatures below 10-12°C. Symptoms of this include severe growth stunting, especially in crops like cucumbers and tomatoes, particularly in their early stages.
- Sometimes, a “false plasmolysis” appears in certain cells due to a sudden increase in membrane permeability, causing leakage of dissolved substances from the cells. This leads to weakness and a reduction in the accumulation of solids, particularly in root crops like potatoes and beets.
- Internal famine occurs due to increased respiration rates at the expense of photosynthesis, resulting in nutrient deficiency. The plant begins to draw elements from its leaves, showing symptoms of nutrient deficiencies, especially potassium, magnesium, and calcium. These include leaf margin burning, spotting, and blossom end rot, especially in fruiting and tuber crops.
- Reduced photosynthesis due to damage to the chloroplast membranes from low temperatures. This is a significant problem for cucurbits (e.g., cucumber, melon, zucchini) and beans.
- Transport inhibition occurs, where water and nutrients are completely blocked in low temperatures, affecting crops like sugarcane and most fruit trees, including olives.
- Respiratory dysfunction and accumulation of toxic substances, such as acetaldehyde and ethanol, occur due to halted aerobic respiration, causing premature plant aging at the expense of dry matter production.
So, what treatments can help the plants get through these conditions with minimal losses?
- For crops currently being planted with dry seeds or grains, soaking them in a solution of potassium nitrate and mono-potassium phosphate at a rate of 1.8% each can enhance absorption in cold weather, for crops like wheat, barley, and later, beans.
- Adding activated carbon to the planting environment and root growth can increase absorption rates in cold soil temperatures, which is very important.
- Look for treatments that increase the activity of the peroxidase enzyme or those that slow down chlorophyll breakdown and increase its regeneration during the day to boost fatty acid content.
(I recommend reading the book “Plant Breeding under Various Stress Conditions and Low Input Resources” by Mr. Hamed El-Saidi, 2005.)
#Second: Here are some urgent recommendations during this period of climate fluctuations:
For root crops (e.g., potatoes and beets):
- It’s crucial to inject about 2-3 liters of phosphoric acid after rainfall, followed by calcium spraying, preferably using carboxylic acids, and using calcium oxide instead of calcium nitrate.
- Additionally, apply 10 kg of potassium sulfate per acre through injection.
For winter potatoes, particularly those planted in October and November, these conditions help the spread of aphids on potatoes. Monitoring should focus on lines near bridges and roads (where dust accumulates) as they are usually the first to get infected. Once three aphids are seen on a leaf, start spraying insecticides (without mixing with nutrients).
Despite the high humidity and surface moisture favorable for late blight disease on potatoes, increased daytime temperatures will prevent the disease cycle, as it thrives in cold, wet conditions. The optimal temperature for sporangiophore formation is 18-22°C, and for zoospores, it’s 10-13°C. For germination, zoosporangia require high humidity (100% relative humidity), which is why disease spread increases during cold, rainy, or foggy weather.
For beets:
- The August and September plantings need careful management. Beets don’t like excess moisture around the root zone, so avoid increasing nitrogen or urea in clay soils, which can lower sugar content. Only apply 80 units of nitrogen in the first three months.
- Be sure to stop irrigation if rain is expected and apply a boron spray at 60 and 90 days after planting. Keep an eye out for aphid infestations.
- According to plant disease prediction programs, the climatic conditions are conducive to the first outbreak of Cercospora leaf spot on beets, a rapidly spreading epidemic disease.
For winter vegetables (e.g., tomatoes, peppers, cucurbits):
- Increased humidity and surface moisture require urgent preventive sprays against fungal diseases that thrive in high humidity, such as downy mildew on cucurbits and early blight on tomatoes.
- Also, spray against aphids, thrips, and melon fruit fly larvae when pest levels reach critical thresholds. Consider spraying with nutrients, amino acids, and growth stimulants to help plants resume growth after periods of slowed nutrient uptake due to high humidity and waterlogged soil.
Important forecasts due to increased rainfall and humidity:
- Expect a rise in beet fly populations and melon fruit fly larvae.
- Increased risk of bean fly damage to the neck region, which can lead to fungal infections.
- A significant rise in whitefly and leafhoppers, which spread many viral diseases, including the common bean mosaic virus.
- The high humidity and fluctuating temperatures will also trigger fungal diseases such as late blight on potatoes and tomatoes, downy mildew on cucurbits, and rust on aromatic medicinal plants.
#Quick Recommendations:
- Wheat: If recently planted and exposed to heavy rain, check for water accumulation and reseed if necessary. For wheat that has already germinated, add 3 liters of 80% phosphoric acid with the next irrigation to boost root activity under conditions of low oxygen due to soil saturation.
- Beets: Urgently apply preventive sprays for Cercospora leaf spot using copper oxychloride alternated with Obis pesticide. Add calcium boron with care to avoid over-irrigation and any nitrogen or humic sources.
- Winter potatoes (40-70 days old): Apply preventive sprays against late blight using active ingredients like Fenamidone and Metalaxyl alternated with copper oxychloride. For fields older than 70 days and affected by the twisting virus and early blight, apply local sprays on infected areas with Polyram or Del-Cab pesticides.
- Garlic: Reduce moisture around plants, extend intervals between irrigations, and treat yellowing leaf tips (likely potassium and magnesium deficiency) caused by cold temperatures or waterlogged soil. Also, inspect for onion fly infestations.
- Onions: If yellowing occurs in seedbeds, check for phosphorus deficiency due to root absorption stoppage after waterlogged soil following rain.
Hope these tips help you manage the weather challenges!
