NDSU Crop and Pest Report

Plant Science

ISSUE 8  June 20, 2002



The North Dakota State Seed Department services have expanded to include seed and grain production tracking and documentation for specialty crops. The new services verify that specialty crop production and segregation are maintained from the seed source to harvest, handling and processing. They can provide unbiased third party inspection and testing that assures your customer that your product meets their requirements. NDSSD will work with each IP client to design a program that fits their individual requirements. Their diagnostic lab provides genetic testing with documented results for seed sources and final product. The following services are provided:

For more information call Tom Sinner at 701-231-5400, at the State Seed Department.

Source: The North Dakota
Seed Journal newsletter
Summer 2002



Hail has been reported in some areas of North Dakota. Prior to crop jointing hail most often has little or nor effect on yield; however, as the crop approaches reproductive developmental stages (head formation in the early boot) injury to the growing point is more likely and leaf damage or loss has greater impact on yield.

Destruction of leaf area on young plants is seldom as serious as appearances may indicate. During early development the growing point is below the soil surface, making it less susceptible to injury. With this protection, small grains can suffer loss of above ground foliage without dying. If the growing point of small grain is not damaged the plants will likely recover.

When hail causes damage, it is advisable to wait several days after the injury occurs to make an accurate determination of injury. After this period, new growth on plants with uninjured growing points can be observed. If no regrowth is observed, the stem of the plant may be split to inspect the growing point. The growing point should be white or cream colored. Darkening or softening of the growing point usually precedes plant death. When the growing point moves above the soil surface at jointing in small grains it is vulnerable to damage.

Wheat and barley typically produce seven to nine main stem leaves. When leaf injury occurs at the three to five leaf stage most tillers have at least two leaves that have not emerged and are undamaged. The flag leaf, the last leaf produced on each tiller, is the most important leaf; if it remains undamaged throughout the growing season the yield potential will remain largely intact.

When severe injury from hail occurs to small grains after jointing plants still have the potential for recovery by initiating new tillers. Precipitation that usually accompanies hail storms will help stimulate tillering. Potentially, tillering can restore yields to acceptable levels.

Additional information can be obtained from NDSU Extension bulletin A-934, Replanting After Early Season Crop Injury. This provides excellent information on evaluating injury, however, this late in the growing season replanting is not advisable! Much of the cereal crops in areas affected thus far were probably not injured beyond the point of recovery.



Hail damage to crops occurs somewhere in the state every year. Reports have already been made of hail damage in some areas in the past 3 weeks. When hail damage occurs on corn, soybean, dry bean and sunflower early in the growing season, replanting is possible; but deciding whether to replant is usually difficult. Total stand reduction, leaf loss, stem injury, weed control, and calendar date are factors to consider when making this decision. At this time ( late-June) its too late to consider a replant.


The growing point remains below ground 2-3 weeks after the plant emerges (5-leaf). If the growing point is not damaged, corn will recover and perform better than replanted corn. Split the stalk down the center and inspect the growing point. If normal, it will appear white in color and firm in texture. Injured growing points will appear brown or discolored 2-3days following the hail. Complete loss of leaves early to corn when small usually does not greatly affect grain or silage yields. Corn in the silking and tasseling stage when damaged by hail can result in severe yield losses.

Soybean and Dry Bean:

The growing points of beans are located in the top of the plant and in leaf axis. Growing points of beans are easily damaged by hail soon after emergence. Regrowth will not occur if hail stones cut the stem off below the cotyledonary node. If the tip of the plant is damaged, regrowth can occur from one or more axillary buds. Bean stems may be bruised or broken. The damage may not be severe enough to kill the plant. However, the plant may lodge later as the callus tissue is weak and cannot support the pod weight. Reduction in soybean stands to four plants per linear foot of row in 30 inch row spacings can still produce fair yields. For dry beans one can get down to two plants per foot of row and still get fair yields.


Sunflower may be more tolerant than beans, but the degree of hail tolerance depends on the intensity of the hailstorm and the stage of growth. Sunflower is least tolerant during the seedling and budding stages, and most tolerant after flowering. Hail damage may be direct or indirect. Direct damage results from stand reduction, loss of recoverable heads because of severely bruised or broken stems, and head shatter at later stages. Indirect damage results from defoliation and disease infestation to injured plant tissue. .

Research conducted on simulated hail losses in sunflower indicated that a one-to-one relationship does not exist between stand reduction and yield loss. A 50% stand reduction resulted in only a 28% yield reduction. Defoliation of sunflower by hail was reported to be most damaging during the bud stage. Defoliation of 80% at the bud stage resulted in yield reduction of 53%. Whereas 80% defoliation at the 50% mature stage resulted in only a 12% yield loss.


Plantings in seedling stages can have stands reduced by 50% and still produce acceptable yields. An average stand of 11-12 plants/ft2 can be reduced to 4/ft2 before yield losses exceed 10 percent. Prior to bolting and flower development, canola can withstand hail without much economic loss. Canola with leaves that are torn and shredded suffer only partial loss, while leaves bruised on the main vein or torn and broken will be lost. Leaf area destroyed will result in seed yield loss. Seed yield losses in canola is approximately 25 percent of leaf area lost. If leaf defoliation is 50 percent, then yield loss would be approximately 12.5 percent.

Canola plants injured in late bolting or early flowering stages seldom die. The well developed root systems and ability to rebranch and develop secondary flower clusters help the plants recover. When buds or flowers are destroyed, the canola recovers rapidly by development of flowers which normally would have aborted. New branches also develop from growth buds lower down on the plant. Seed yield loss will depend on both percent leaves and branches lost. For example, if canola has 60 percent lost branches 7 days into flowering, seed yield loss is estimated at 18 percent, whereas 21 days into flowering, yield loss would be an estimated 60 percent. If hail strikes late, such as during pod filling or ripening, plant recovery is not possible. The time needed to develop new growth, flowers and mature is limited before a killing frost. Canola seed yield loss if injury occurs at the ripening stage depends directly on the loss of branches, individual pods and seed knocked out of pods. Severe hail losses have occurred in canola swaths in past years.

Duane R. Berglund
Extension Agronomist

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