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>> hello, everybody. this is the department of brown bag lunch. we are walking around looking at trees on the hottest day of the year in san francisco. there's a few bicycles coming and going. it must be a long hot day to be bike riding. we're joined with carla short who's the city urban forrestor. is that right? >> uh-huh. >> she's going to look at trees and talk about tree issues. and we invite your questions. she knows all about trees. we have a whole pile of trees ready to put b put in the

ground. what kind of trees are they. >> victorian box trees. >> what size are they? >> a 24 inch box, which is the new standard. we do at least 24-inch box or larger unless the site is to constrained that we have to go small every. er -- smaller. it increases the survival rate of the tree. so this is our new standard. >> it takes a little while until they can adapt to the location. how long does that usually take? a couple of seasons? >> it does. we normally will water a tree throughout the dry season which we estimate about nine months of the year. so if it is -- has not rained, we have to go water the tree.

once it is established, then it does not need our help. >> there's a particular problem with trees that are in boxes or in planters or that are not planted in the ground and that's that they have a lot of area of evaporation. so trees like this that are sitting in boxes in sidewalks need a lot of care and a lot of water. >> that's right. we would water these extra so several times a week while we are waiting. one of the reasons why we try to get trees planted in the ground rather that in raised plantearns is because you only have to water for a few seasons. if you put it in a planter box you're going to be watering it for the rest of your life >> you often see dead plants and

that is because they dry out so fast. >> it says -- ud -- undulaem mean? >> undough -- undolatting. what can they tell us? >> form. >> form is s. so that's a good thing we can note. that's what we call standard form. which when you are talking about a tree, it looks like a tree. it has one trunk. the other forms are multistems or multitrunk. so for street trees it is important to have that standard form because we need to have clearances for pedestrian and vehicular access. >> quantity 50. well, hmm, guess there are 50 of

them. what does this mean? l.m." >> it means lance scape maintenance -- landscape maintenance. we know which project they are for. >> and this nursery would have said something about the fertilization history. >> that's right. and they do to have that on there. we try to get trees established into their natural environment. once we get phlegm the nursery, -- we get the nursery, we will try to already have them established. we don't do a lot of fertilizing. if there is really bad soil conditions then we might amend

the soil. >> do people need to fertilize their trees. >> typically they don't if you are planting in your own yard, and if they have some products that are root stim lay tors, there are fungi that will help your roots adapt. you can scatter it around the roots and water it in. and it helps those roots to develop and get adapted. but generally most trees don't need a lot of fertilization if your soil conditions are very bad, you might want to amend the soil, i always like to do organic soil. we work with a variety of nurseries in the area. so there's not just one. we have some nurseries where we get a lot of the same species that ke with count on them. sometimes we have to go a little bit further up field. there are a few nurseries that

they are not based in the city. they are based in the nearby areas where there is more land. and they have to be acity-approved vendor. so we are restricted -- a lot of times is having that paperwork. everybody is qualified, they just haven't done that. but there are some good

>> this is newly constructed within the last month or so, new sidewalk. what can you tell us about this? >> as i said earlier, spikas a hearty urban tree. they have aggressive roots and sometimes they daniel the

infrastructure, with the fica tree, we can repair the sidewalk around it, it doesn't mean we str to remove the tree. but sometimes if the roots are everywhere, the numb of roots to cut or shave, would render the tree unstable, in this case, we were able to keep the tree, a nice upright ficas tree. we expanded the base. and we keep the necessary path of travel for pedestrians but if we open this up so we don't cut a big root. we try to preserve as many roots as we can. >> the path of travel, the city has a minimum travel standard, i believe it is 48 inches. >> it is. >> we easily maintained thap about we see where trees encroach on that or are tripping hazards. >> we never want to go less than 48 inches in the path of travel, ideally, it is more than that, but if it is scrult of losing or

keeping a tree we'll shrink down to whatever we need to. >> let's move around the corner, to this. see if we can get in the shade over here. here we have one of those trees. what kind of yuke lip tass is this? >> this is the dollar one. >> i remember that from my tree classes. >> warren knows as much as do i, he's just in the wrong department. we're going to recruit him. >> so, what they call silver dollar. the leaves are the shape and size of silver dollars. silver dollar. >> this is another tree that we see fairly often in san francisco, although, not a tree that we, currently recommend as a street tree, but we'll never take out a tree because it is the wrong species. it, there has to be some reason to remove it. >> how about this giant lean, is

that a reason to be concerned? >> it is a reason to be concerned not to remove it. if we were seing this sidewalk coming up, on this side, again, then we would be a little concerned that the lean is increasing and it is lifting the sidewalk and at that point we might say, you know, it is not really safe, you can't repair the sidewalk, the tree will have to come out. the lean of the tree is not in the path of travel for pedestrians and not over the street. it is not a huge problem in terms of, of the access that we need. and that would be another reason why a tree might come out. if we had this level of lean over the street, we wouldn't have access for vehicles and it might have to be removed for that reason. part of the challenge with this is young tree care can make all the difference. and it is a little guy that we can give you, and you can pick up the plantings, that talks about how to prune a young tree. pruning that you can do, in the first five, five to seven years of a tree's life can set it up

to be a great fruit tree, basically what you want it to be is well staked and upright. >> if we we look at the next tree, this is a beautifully upright, perfectly proportioned tree. >> it is gorgeous, i'll send people to this tree, this is the brisbane box. we plant a lot of trees from australia and new england. brisbane box, they're well adapted, they have trees that will do well in our climate. a bigger chaltoning plant in many parts of the san francisco, the micro climate, we have windy area, really foggy areas and part of the reason we don't have native trees, is there weren't a lot of native trees in those climates. they're shrubry and branchry and they don't make good street trees.

>> a good street tree is a tall tree that hasn't been topped or hacked back to get under wires. one reason this is lovely, is it is allowed to achieve its actual frm and a lot of times you see this lollipop trees or trees that are packed back to get under wires. on this particular street, we don't have overhead wires, we'll release them and they can definitely more naturally. >> this is a great street tree, it is a new tree, it is a hearty urban tree but it didn't have some of the problems of a ficas. it is more like a column at maturity, it gets good size, but it is less prone, it will do sidewalk damage or infrastructure damage sometimes. but the roots are not as aggressive of the fica roots. it is another tree we love in urban conditions, it is very reseal yebt. >> name again.

>> brings -- brisbane box. >> if we look across the street, you see a newish building, you see street trees along the face of this new building, part of the city requirements is when you do a new building, you're required to plant street trees, unless you get an exception because there are problems with the utilities underground or driveway interference or something. this is a case where there was a brand new building and they were required to plant three trees. the rule was one treat for every 20 feet of curb face. >> what are these? >> toif look closer. >> they not only have to plant them, they have to maintain them too. >> that's right. in some cases, the code said shall plant and we would plant and they would take them out. that has been since corrected in the code. >> luckily. but it can be a little

challenging because we will have deefler, who builds a building and then sells it and the property owners don't realize that the city doesn't maintain those treings that they have the maintenance responsibility. it is not uncommon for us to come across new tree that is are perfectly staked and dead. and as soon as the building changed hands, they didn't realize they had to do anything. >> okay, look at this thing, and look at this damage to the bark here, caused probably by somebody running into it with a car or truck or something. >> that's right. yeah. i imagine, given that we're right next to a driveway and a grand jury, this is probably a bad -- backing up attempt, or, you know something. unfortunately like that. >> that really does damage a

tree and ultimately it will compartmentalize the damage, it won't affect the tree. the tree has other problems. tell us about this. >> this won't kill the tree, there are a number of things that probably will and actually, we can't look at the street side of the tree, but we've got a whole lot going on here. >> let's look out on the street side here. this tree has been repeatedly damaged in the trunk here, at the base of the trunk. what you can see is that doesn't really look like real live wood. and that's because it is not. it is, it is deadwood, that has grown, the tree has grown around, it wasn't able to fully heal from the wound. the other things we're seeing, i don't know if you can see, but it looks like the tree is almost flat, when you look at the sides here, instead of growing thrike this, where you have -- you have a brord base. this hasn't been producing any healthy wood on the side of the tree for some time, that's a

structural problem, what it means is the tree is, has deadwood there and is not producing live wood, it is potentially, that's a really high, breaking point. where the tree would have -- potential for failure. and in addition, the poor tree has had a lot of problems over the years. it looks like there was probably a low branch here that got -- maybe pruned off, but there's another branch here that probably got ripped off, what you can see is, the tree has a much easier time trying to, for form wound wood which is how it compartmentalizes the wound. it is essentially forming a scab, when it can't to that, when there's like shredded pieces, where a limb gets ripped off, for example, the tree can't really form that nice scab around it, because there's too many jagged edges. it is like human beings, you can imagine a narly scrape is going to be harder to heal over and scab up than a little sa