Use irrigation if it’s available

Some field producers are already using irrigation. Sitting and hoping on rain only hurts the plants more. If you have the ability to irrigate before a deficit occurs, you can have a lasting impact on the plant’s ability to move water, which will have beneficial effects.

During a drought, smaller xylem vessels are formed. The smaller diameter xylem vessels reduce the hydraulic conductivity of the plant.

This means that even after the drought ends and water isn’t limiting, there is a period during which the plant still has a reduced ability to move water. In addition, smaller leaves form during a drought.

This is because cell expansion, and thus, leaf and root expansion, are a function of turgor (water pressure inside the plant) pressure.

Some species will recover quickly once water is again abundant and rapidly grow (and grow larger leaves than what grew during the drought); other species will not be able to recover.

Photosynthesis is not as sensitive to drought as leaf and root expansion, but photosynthetic processes are affected by the water status of the plant, and photosynthesis is a function of leaf area.

Those plants which experience drought and aren’t able to resume growth after the drought period will have a reduced leaf area and, most likely, a reduced biomass.

Irrigation does require a water source, money and more management in addition to the pump and pipe. Be sure you have enough water to irrigate the way you desire.

We are losing 0.2 inches of moisture per day to evaporation and transpiration. At 91 degrees we begin to lose 0.3 inches per day.

We are losing an inch every five days and no real rain predicted. Drip is great for seedling production and budders, (crop at close spacing) but less economical for B&B.

Drip requires time to decide when to turn it on, to check and repair leaks and then time to determine when to turn it off. Instruments are available to determine when to turn it on and off. It determines when the moisture level is low and when there is sufficient.

I hated to see two women walking behind a 500 gal tank on a trailer watering plants, each with an inch and half hose last week. But then I really hated to see men carrying large buckets and using dippers to water individual plants. It might keep new liners alive; but surely there is a better way.

‘ Some of this information was provided by Amy Fulcher, Univ of Ky Extension Associate – Nursery Crops

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I need to readdress something from last week. I wrote about cutting corners and saving money and sidedressing half of your normal amount. There is no need to sidedress if it does not rain to move the nitrogen into the soil. It would be lost to the air. I would wait for definite rain.

I understand mowing the middles, roadways, etc less frequently to reduce costs, but I must recommend providing decent weed control around the crop, to reduce moisture loss to the weeds.

Management must decide to use a hoe, cultivation, pre-emergent herbicides or an Enviromist to keep the row clean. Pre-emergents are lost without rainfall to activate them.

Research has proven all the harmful effects of weed competition over and over. Our freeze and drought stressed crops do not need weed competition to add to the damage.

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Potato leafhoppers generally arrive about this time. They cause short internodes, cupping, and black leaf margins that is referred to as ‘hopperburn’ on red maples. They do not overwinter here and do not become resistant. Sevin, Diazinon, Dursban, Talstar, Tempo, Decathlon, Scimitar, Flagship and Discus are labeled and suggested. It is more important to control them on smaller trees when the growth is critical.

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American boxwoods with only the outer shell of foliage killed do not have to be sheared. The new growth will grow, the dead will fall away and some labor can be saved. Koreans will require most of the dead cut away as soon as possible.