Black Jewel Raspberry


I have about 10 different varieties of raspberries in my Toronto yard.  They were all planted last year as two year old canes.  This spring I clipped back all of the two year canes planted last year and kept the fresh canes that started last year.  I have noticed as the leaves have started to come in on the black jewel raspberries that they are splotchy with a bit of a brown around the edges.  Is this an issue?  I have been reading that it could be a virus.  If so, should I remove the entire black jewel plant immediately and destroy it?

The canes are planted in clay soil, full sun, and fairly wet.



The browning edges of your raspberry plant could be caused by a number of things – nutrient deficiency, over fertilization, lack of water or diseases such as Rust fungus, Verticillium fungal infection or Raspberry mosaic virus.  Below, you will find brief descriptions of each of these so that you can take a closer look at your plant, make a more accurate diagnosis and then decide on treatment or removal.

Nutrient Deficiency – leaves turn brown along the edges which is called Leaf burn.  This can occur in raspberries when one or a number of essential nutrients are not readily available in the soil for the plant to take up.  A soil test can determine which specific nutrient is needed.  Other signs of nutrient deficiency include yellow / light green leaves & stems, yellowing between leaf veins, stunted growth and foliage loss.  To help your plant regain its vigour, fertilize your raspberries with a balanced fertilizer (20-20-20) carefully following the directions for use on the fertilizer package.  Ideally you should do this feeding in the spring when new growth emerges, then again in May and again at the end of June.  Since the weather this year has been somewhat colder than usual, if you determine this is your problem, I would suggest doing a feeding now and then a second one at the end of the month.

Overfertilization – as stated above, fertilizer can fix nutrient deficiencies but raspberry leaf edges can become brown if too much fertilizer is applied.  Other signs to look for include yellow & wilting leaves, slow or no growth, fertilizer buildup on the soil surface and leaf loss.  In particular, nitrogen and chloride fertilizers can cause damage when applied too liberally.  If you think this could be your problem, you may be able to save them if you flush the soil with water.  Using your hose, give the soil around the plant a thorough soaking then allow the plant to drain.  Do this several times leaving one hour between flushing’s.

Lack of Water – raspberries need a good supply of water or they will quickly show signs of drought stress.  Brown, shriveled leaves, shriveled fruits and dry, sinewy roots are sure signs that your plant needs some hydration.  Once your plants are given a good soaking and damaged foliage is removed, they should recover.  On average raspberry plants need 1 to 2 inches of water per week during the growing season and up to 4 inches of water weekly during the harvest period.  Avoid watering with overhead sprinklers because moisture left on the leaves may increase your chances of disease.
Disease – A variety of diseases cause raspberry leaves to turn brown, see below for the major culprits:
Rust fungus – causes leaves to turn a splotchy reddish-brown.  Infected plants should be removed and destroyed to prevent it from spreading.  Place all debris out for kerbside pick up with your other garden waste and do not put in home composter.
Verticillium – another fungal disease that causes leaves to yellow & brown, as well as browning and killing the actual plant cane so carefully check the cane health as well as the leaves.  Verticillium lives in the soil for years, so it is important to remove and destroy plants as instructed above.  Do not re-plant raspberries into this part of the garden.
Raspberry mosaic disease – causes leaves to turn a mottled yellow-green with brown tips and stunts plant growth.  This is a viral disease transmitted by garden pests such as aphids and cannot be cured.  Prevent infection by planting varieties that are resistant to the disease,  Aphid populations can be controlled by regularly using a hose to spraying raspberry plants with a strong stream of water, early in the morning, to knock the pests off of plants.  Lady bugs/beetles can be purchased at some nurseries and have proved to be a reliable method of controlling aphid infestations.