Area crops showing signs of heat and drought stress

Historically, July is the driest month of the year, and we are getting numerous reports of vegetable plants showing heat and drought stress such as curled leaves on tomatoes and potatoes with thin and stringy vines and cucumbers and pumpkins are not spreading out like usual, according to agricultural expert Bob King.

The months of July and August highly influence plant growth, so it pays to guard against water stressing crops and gardens by closely monitoring rainfall, soil moisture content, penetration of moisture especially during the most critical time in the development of a plant. Typically, flowering and fruit enlargement for many crops are critical times to keep soil moisture at optimal levels.

More specifically, root crops such as beets and carrots have a critical time during root enlargement. For cabbage and lettuce it's during head enlargement. Tomatoes need abundant water during early flowering, fruit set and enlargement while peppers need the water most from planting through fruit development. Sweet corn needs water most during tasseling, silking and ear development and for potatoes, tuber set and enlargement are critical times.

Because of wet conditions during early spring, many plants did not push deep roots. Because most crops have not developed good root systems to help get them through the drier times, it's very important to be prompt in providing them adequate water.

How long and often should you water? If it's a week of cloud cover and 80 degree temps, the equivalent of an inch a week may be enough to get by for many crops. But if it's dry, windy and 90 degree temps, and crops are planted in a sandy soil, the equivalent of two inches a week may be necessary.

Water sensitive crops like peppers, lettuce, potatoes, and many types of flowers are shallow rooted crops, usually within six to eight inches of the top soil, and are not very effective at either extracting or holding onto water. During dry conditions, water these crops more often like every two to three days and only for short time intervals because the water only needs to soak into a six to eight inch depth.

Tomatoes and squash tend to be better at extracting and holding on to water than peppers and lettuce and usually have deeper root systems of up to a foot and sometimes more. Consequently, water these types of crops on a three to four day frequency, but water for a bit of a longer time period to make sure the moisture reaches at least a foot depth.

Crops like corn and pumpkins, because they can have root systems as deep as three feet or more, typically get only 60 percent of their moisture requirement from the first foot of top soil. So these crops can go without water for a longer period of time, except during the flowering and fruiting stage.

Try to irrigate when the Evapo-Transpiration (ET) rate is at its lowest in the day, which is usually in the early morning or late evening.