July 19, 2020

GDD Update and a few other things 7.19.20

Oops – a little behind.  Small family excitement which is now under control.  Things happen, don’t they!


I can feel the GDD rise as I sit here – moving to fan zone soon although I do detect a breeze.


GDD                       July 19                  July 24


Champlain           1205                      1314

Geneva                 1331                      1452

Riverhead            1568                      1708


Nothing to add at the moment.  You can find previous emails at https://blogs.cornell.edu/ornamentalcropsipm/.  Search for GDD and they should all pop up.



Here are some references and things that popped up during the CTFANY Summer Zoom meeting.  Thanks to all who attended!


pH ranges for Christmas tree species https://www.canr.msu.edu/christmas_trees/horticulture/nutrition/soil-ph


Working on finding the mycorrhiza information I thought I had…


Stay cool – pay attention to the potential for heat stress!  I hear the lake calling me!


July 19, 2020

IPM Update 7.8.20 – mildew mapping

Cucurbit and basil downy mildews move into NYS from (usually) the south and are being mapped.  You can check in on the maps yourself or sign up for alerts


While these are more common in field production, I have seen basil downy mildew in greenhouses.


Cucurbit downy mildew https://cdm.ipmpipe.org/

Alerts – https://cdm.ipmpipe.org/alerts/

Confirmed in Western NY


Basil downy mildew  https://basil.agpestmonitor.org/map/

Alerts – https://basil.agpestmonitor.org/alerts/

Confirmed in PA


The websites also have links to photo galleries for ID, discussions of threats and risk, and if you really look (I can’t resist anything labeled Interesting Links) – a link to the Mt Olive Pickle Company!


Have a great day!


July 19, 2020

Christmas tree IPM Update 7.8.20

Have you noticed it is dry? Might have some disease management benefits, but the detriment to the tree overwhelms that – especially for newly planted trees.  And for larger trees, we don’t always see the effects immediately.  I wish I could solve this problem for you – and for me, too.


So if you want to know how dry it is and what the predictions are, here are some resources.




http://www.nrcc.cornell.edu/regional/monthly/monthly.html – click on percent of normal monthly precipitation.




http://newa.cornell.edu/# – you can always wander around in NEWA to find all sorts of environmental information.


July 19, 2020

Christmas tree IPM Update 7.9.20

Ah,  Japanese beetles – 2 questions no less.  Yes, they can be a problem on Christmas trees – I have seen them on the leaders and they can chow down because they are big.


The pheromone (which is what is in those hanging beetle traps for sale everywhere) is good at attracting the adults but not good at getting them all in the bag so don’t bother with traps as a control measure unless you can blanket the whole area- or attract them to some other area where they aren’t doing damage to plants you want.  They are useful to monitor when the adults arrive and then take it away.


If just a few trees have adults – knock them off into soapy water (I can hear your eyes rolling) (A note from a reader –

Knocking the beetles off into soapy water is actually pretty quick and easy if you do it in the morning. They fly off if you wait until later. When you crush them you call in more according to Brian Nault (Cornell Entomology faculty).)


For treating adults 1029-2154 GDD for foliar sprays and it may take several applications.  They tend to be localized where I have seen them – so you wouldn’t have to spray everything – but since you are scouting your fields you will know where they are.   And write it down for next year – to learn if they tend to appear in the same place every year. (I don’t know the answer to that.  One would think they would lay eggs near where they feed, but they have preferences for egg laying sites – grassy areas – and can fly.)


There are quite a few active ingredients listed in the Guidelines for adult management (get your own copy here so you don’t have to wait for me – https://www.cornellstore.com/product/149958)


Check the labels to make sure that Christmas trees or conifers are mentioned as well as Japanese beetles.  Pyrethroids, like bifenthrin, cyfluthrin, lambda cyhalothrin and permethrin last 2-3 weeks. There are some imidacloprid soil applied pesticides that are systemic. All of these pesticides are toxic to bees and other pollinators so use appropriately.  I need to ask some questions on some other active ingredients so more information soon.


Grub control is in the fall when the larvae are fairly small and before they have migrated lower in the soil profile.  You really should sample for grubs before applying anything to find out where they are – which makes it a little more difficult.  Check in the areas where you have seen adults, sandy and grassy areas seem preferred (for all white grubs – and id is a little complex).  There are some biocontrols – nematodes, Bacillus popilliae or milky spore disease – which have variable results and are often better in warmer parts of the state.


Drier soils are less preferred – some good out of this rain-free period.  But adults will often move from irrigated grassy areas like lawns to other areas to feed.


Timing is important for both grubs and adults

July 19, 2020

Christmas tree IPM Update #2 7.9.20

Another question in the Inbox that I can relate to – how to get rid of bedstraw and bindweed.  Both are annoying as they climb the trees and interfere with other things you are trying to do.


Bedstraw is possibly easier – there are 2 primary kinds that I see – and they seem very prolific this year.

Smooth bedstraw (Galium mollugo) has white flowers, 8 leaves at a node and smooth stems. It is perennial.

https://www.oardc.ohio-state.edu/weedguide/single_weed.php?id=4 The pictures aren’t great but the information is good.


Catchweed bedstraw (Galium aparine) looks very similar but has hooks on the stems and leaves, leading to another of its names, Sticky Willy.  It is an annual – sounds good, only lives one year – but wait, the seeds are prolific and they stick, too, so it is easy to spread it around on clothes, fur, feathers, equipment… https://plants.ces.ncsu.edu/plants/galium-aparine/


We are a little late on bedstraw – in Ithaca anyway – as it has gone to seed and is likely to be spread while removing it.  Try and get it out of the field – particularly the annual sticky one – when it is in flower or before (the flowers make it easier to see).


From the Guidelines  – and only G. aparine is listed but it is likely that G. mollugo is affected the same way –

Pre-emergence – Goal 2XL – a good idea where you have had the annual one the year before

Post emergence – Goal 2XL and Roundup Pro (or equivalents)


There is more than one bindweed, too – most commonly Field bindweed (Convolvulus arvensis) and hedge bindweed (Convolvulus sepium). Both are perennial – and have taproots so they are very difficult to eradicate.  This is another of those weeds that are best controlled in the late summer.  They need to be actively growing but at that time, the herbicide will be translocated to the roots, giving better control.  It may still take several years.


I have an ID comparison if you are interested – too big to send on this listserv or you can look here under concolculuc – https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification.aspx


Convolvulus species is listed in the guidelines

Post emergence control – Finale (glufosinate ammonium) and Roundup Pro – both are non-selective meaning they will damage nearly all plants.


However, the question was how to control them without hurting the trees.  The only way is to use a directed spray and not contact the trees.  Often the plants that are most problematic are literally entwined with the tree so no contact is almost impossible. Shielded sprays and sometimes just cutting them out, as well as trying to control them before they get too big will help.  Trying not to let them go to seed helps in the long run.


Have a great evening!