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March Highlights

Things to watch for during March

From our experience of samples we have received during March in previous years in the OSU Plant Clinic, this page will highlight some problems that may occur this month. The mild winter this year means we are ahead in terms of plant growth.

Abiotic disorders

The cold snap we had during last November is showing its effect now. For example we are seeing blueberries with dying and browning cambium along the length of stems, and darkened buds that do not expand. Secondary pathogens may invade the dead tissue and appear as dark necrotic lesions along stems.

blueberry cold injury

Nutrient management is an important part of growing healthy plants and regular soil testing can identify problems that may be corrected. This article shows how to interpret your soil test results, and also some of the problems that arise when nutrients are out of balance. Requirements for specific crops are available through the OSU Extension Catalog.

GENERAL NOTE: Taking action this month near bud break for many crops (such as lilac, rose, peaches, and hazelnut) with timely disease and pest management programs will reduce the need to watch for things next month and this summer.

Fungal disorders

Look out for purple blotch on blackberry, caused by a fungus that produces red margined, purple lesions on canes. These lesions can develop into cankers that can girdle and kill the canes during spring. Now is good time to scout for these before leaves come out and hide the lesions.

blackberry purple blotch

Anthracnose and perennial canker on apple can be watched for now, especially while pruning. Anthracnose appears on smaller branches, or trunks of young trees,  as small brown spots that develop into cankers. Perennial canker, caused by a different species of the same fungus that causes anthracnose, appears as overlapping concentric rings of woody tissue encircling a central wound. Perennial canker is often associated with the presence of woolly apple aphids, low temperature injury, and pruning wounds. Both diseases produce the bull's eye rot symptoms on fruit.

apple_anthracnoseapple anthracnose

apple perennial canker
apple perennial canker with woolly aphids (in the cracked bark)

In greenhouses now, look out for gray mold and powdery mildews on ornamentals.

Fusarium root and crown rot in field crops of clover may be caused by a combination of stresses, including winter injury, nutrient deficiencies, and wounding. Insects may be a cause of wounding, especially the larvae or root borers and weevils. Plants may be pale and stunted with darkened crowns and roots.

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red clover

Viral disorders

In greenhouses watch for Impatiens Necrotic Spot Virus, we have had recent samples of Diascia and Lobelia with this virus. Transmitted by thrips, this virus causes discolored, distorted leaves with necrotic spots, as well as stunting.

lobelia INSV

Symptoms of Fall infection of Barley Yellow Dwarf Virus (BYDV) on fescue, rye, wheat and many other cultivated and wild grasses may first appear in the spring as yellowish leaf tips (reddish in oats). BYDV is transmitted by several species of aphid.

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wheat - bydvwheat

Bacterial disorders

Damage caused by species of Pseudomonas including Pseudomonas syringae, on woody ornamentals are typically seen at this time of year. Note that Jay Pscheidt says this year he has not seen much Pseudomonas. These bacteria overwinter in diseased twigs or as epiphytes on healthy wood. Tissues that have suffered injury from frost, as well as from pruning, unsuitable soil pH, poor nutrition, or infection by other pathogens, are predisposed to Pseudomonas diseases and exhibit a variety of symptoms.

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lilac-Pseudomonas syringae





 see also "The Plant Clinic Year"