1996 Nursery Inspection Summary 



Tom Durkis 



Tf he 1996 winter was a typical one, but after that, 

 the growing season was anything but normal. 

 Cold temperatures early in the season resulted 

 in plant damage ranging from discolored 

 leaves on unprotected pansies to whole truckloads of 

 frozen annuals. Several department stores were dis- 

 couraged enough not to even bother with replace- 

 ment orders. Local growers less dependant on 

 shipped merchandise fared much better. Rainfall was 

 plentiful all season and was consistent enough to 

 make growing conditions ideal. The survival rate of 

 nursery liner stock and Christmas tree transplants was 

 never better. The perfect spring planting conditions 

 were common over most of the state and nurserymen 

 and gardeners alike could not have asked for any- 

 thing better, except for a little more fungicide. 

 Botrytis was commonly found throughout the state 

 due to these wet spring conditions and thick algal 

 growth in liners caused an increase in fungus gnats 

 (Mycetophilidae and Sciaridae) and shore flies 

 {Scatella stagnalis). Scattered problems with Septoria 

 blight (leafspot) on tomatoes caused severe crop loss 

 for one grower. Cercospera leafspot was detected in 

 one of our greenhouses this year. Shipments were 

 sent out of state where problems arose. The Tennes- 

 see Department of Agriculture contacted us and the 

 matter is still being investigated. The cause of the 

 disease was most likely due to a bad seed source. 

 Most growers were able to contain their aphid prob- 

 lems provided they were vigilant from the beginning 

 of the season. A few complacent growers had extreme 

 aphid populations and consequently were forced to 

 dispose of a large amount of plant material. Western 

 flower thrips {Frankliniella occidentalis] and greenhouse 

 thrips [Heliotfirips haemorrhoidalis) again were the big- 

 gest greenhouse pests for growers and dealers alike. 



A common mistake still being made is the failure to 

 check and isolate incoming stock for pests. The ex- 

 tended cold weather conditions in the spring forced 

 plant dealers to cram their stock together in whatever 

 space was available. This facilitated the buildup of 

 thrips, which quickly spread to uninfested stock. Do not 

 assume that the stock you are receiving is clean and 

 free from pests. Dealers must be alert to the possibili- 

 ties of receiving infested shipments from anyone. 



One of the more interesting finds was a serpentine 

 leaf miner on the leaves of mini-chrysanthemums in 

 the houseplant section of several grocery stores. The 



plants had originated from a foreign country and the 

 pest presumably came in on the host. Adult flies are 

 being sent for positive identification. Leaf miners are 

 members of the family Agromyzidae, species of which 

 affect a large number of plants. One of the most com- 

 mon leaf miners is the columbine leaf miner 

 [Phytomyza sp.). Three species of rose slug (sawfly) 

 continued to be prevalent throughout the season. 

 These sawflies have overlapping cycles and feeding 

 patterns which can make them difficult to monitor. 

 Tarnished plant bug (Lygus Uneolaris) and fourlined 

 plant bug {PoecUocapsus Uneatus) caused significant 

 damage to containerized stock, especially viburnums 

 and weigela, along with vegetables and flowers in 

 flats and pots. These insects are good flyers and hide 

 well, so the plants must be inspected for damaged 

 leaves as well as the presence of the insect. Gypsy 

 moth populations were down throughout New Hamp- 

 shire, but Massachusetts had several problem areas. 

 Nursery stock from infested areas had a large number 

 of larvae hitching a ride to New Hampshire. The lar- 

 vae frequently hide under the cardboard wrapping, 

 going unnoticed to the unexpecting buyer. Later in 

 the season, adult females and egg masses were also 

 found under protective bark wrapping. Another no- 

 table problem found in grocery stores and container- 

 ized nursery stock was French weed or hairy Galinsoga. 

 A member of the aster family, the seed of this weed 

 usually finds its way into gardens and perennial beds 

 through manure. 



Evergreens had a noticeable decrease in the yel- 

 lowing of older needles which was prevalent late in 

 the season the year before. Many insect and disease 

 problems however increased. On fir, high balsam twig 

 aphid {Mindarus abietinus) populations resulted in 

 needle curling ranging from mild to severe. Balsam 

 gall midge [Paradiplosis tumifex) showed up in scattered 

 areas, but caused only minimal damage. Gall midge 

 populations have increased and this coming season, 

 growers could experience major problems with this 

 pest. Large numbers of strawberry root weevils 

 {Otiorhyncftus ovatus) were found last fall invading a 

 nurseryman's house. It is not uncommon for these in- 

 sects to seek out homes as overwintering sites. The 

 larvae of this weevil feed on the roots of almost all 

 evergreen nursery stock, causing substantial damage. 

 Two nurseries experienced serious fir seedling loses 

 from Phytophthora root rot. 



FEBRUARY & MARCH 



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